Chapter 19: Manufacturing Experiment


Right now the amount rubber ready to be manufactured is not really that much.

I will say that I have approximately around 30 kg worth of rubber. Whilst you may feel that 30 kg is a huge amount, it takes quite a bit of time before this much can be gathered from the tree. The Para rubber tree grows in the vicinity of our Bakkudo village and it took me around 30 trees in order to create approximately 250 g of rubber each day. In one month, I made around 7.5 kg worth of rubber. If I collected the sap every few days, I could maintain this process and in about half a year, it will be possible to collect more than 40 kg worth of rubber.

If you wanted to mass produce it, then this kind of quantity wouldn’t be able to cut it. However, considering that there was hundreds of trees growing in the wild, if I collected them all I could obtain a considerable amount, moreover in order to facilitate this process, I could also begin planting the seeds of this tree. If I am not mistaken, this species of rubber tree grows exceedingly fast, and whilst the quantity may not be much, sap can immediately obtained from the tree within the span of several years after the seeds have been planted.

Now then, where should I begin?

I suppose I should start with the shoes first.

Typically, boots are made from the skin of pigs, and as for the soles of the shoes, the people of this world would usually have wood as the base of their shoes. After that, they would perform finishing touches by adding more leather. They did use tanned leather so it is quite durable, however, it’s pretty much as durable as skin can get, besides, putting on these kinds of shoes will feel quite uncomfortable.

Perhaps, I should remodel sandals.

If I cut out the raw rubber in the shape of the sandal and then put a thin layer in the middle layer of the sandal, it will make it much more comfortable. I should also do this for the shoes so that it can act as additional cushioning. Moreover I should combine it with the hard black rubber and place this part at the bottom of the shoe to increase its durability. As for the hard rubber, I’ve already prepared some beforehand so it should be fine.

After creating these type of shoes, I tried putting them on for a moment. Because the size is for adults, it’s a little baggy on me, but I think that it should have increased the amount of comfort.

Well I can’t really tell because it’s too loose on me. But oh well.

I started off by making something simple, and it seems that there is no problems as of yet. The next item I want to make should have a little more impact.

I think that the wheels of wagons can be improved, but because this would take too much time, I postponed this thought until now. Because I need to put pressurized air into the tyre of the wheels, I should probably start by creating a tube to transport the air. If I spent more time on it, there is probably nothing that I wouldn’t be able to create, but for now I don’t know how to make the valve. Ah, wouldn’t it be fine if I just used wind magic to directly insert the pressurized air into the tyre? That’s true, I don’t even need the valve then…

Alright, I think I will give it a go. First of all let’s create the air tube. A long cylinder of about 5 cm in diameter is prepared, and just before the rubber hardens I poured the (brownish colored softer rubber) into the cylinder. In doing this, I created a 4 cm diameter tube that I could push into the tyre to transport the pressured air into it. Another option would have been to create a flat board of rubber which you would just roll into the shape of a cylinder but because it would take too much effort to bond it together, I scrapped this idea.

If I can just combine this tube with the small ring in the rubber tyre, then I can begin to pump air into it. It seems that the small ring which is supposed to connect the two parts together is a little bit bigger than it was supposed to turn out, but it was still within my calculations. Well I will cover the hole out later with rubber so that the air doesn’t leak out, so it shouldn’t really matter that much.

For now, let’s just try it out and start by directly injecting the tyre with pressurized air via wind magic. Ohh, its working. It will be a problem if I raised the air pressure within the tyre by too much, so I should make sure that it inflates enough without exceeding the necessary amount of pressure. In any case, I also checked to make sure that no air would leak out of the tyre, by first placing water within the tyre itself to check for holes.

It was at this point in time that I noticed that I missed a very important thing, I was shocked at myself. If I was going to outfit the wheel of the wagon with a tyre, I should have probably created a more modern looking kind of wheel, like the one they used for cars, right? Up until now, the wooden wheel used in this world could only travel past flat surfaces and it would heavily rock if it were to step on a log or something. That’s right, I completely forgot to make the rim. If things were to go as it were right now, without including the rim, the components of my wheel would probably travel for a few meters before miserably breaking apart.

In order to create a rim, I would actually need to be able to create the metallic outer circumference of the wheel along with the inner parts as well, otherwise it wouldn’t work properly. For now, my magic is not at a high enough level to be able to accomplish something like that. Not only would I need to create metal I would then need to shape it accordingly for it to actually work, because I don’t think I will be able to do this, I guess I have no choice but to give up on this idea for now…

Well it’s not like I was in a rush to immediately create a completed tyre, so let’s just defer the task of making the rim of the wheel until later. Well this would obviously mean that I cannot continue creating the tyre itself, but it can’t be helped. It would be better for me create things that will make me money, what this means is that, I need to create products which are easy to sell.

As far as trying to accomplish this goal, this would probably mean that I should create something like a protective armor with the hard rubber: ebonite. Well because it is already a sturdy material in itself, I don’t think I will need to form it into the shape of an armor so per say. All I need to do is prepare a flat shaped rubber approximately around 3~40 cm in size. To be honest, I wanted to bind the flat surfaced rubber with wire to strengthen it even further, but because I am unable to create the wire right now, I gave up on that idea. Well if I did make a chainmail armor it should be in a square shape, right?

After that I also prepared sling shots of various shapes and sizes, and also the suitable length elastic bands to go along with the various sling shots. In addition to this, I had previously made a rubber glove which I created so that I could manufacture the rubber without getting my hands contaminated. It takes quite the effort to put your hands into this glove and I’ve finally been able to reduce the thickness to about 0.5mm. Of course the gloves I made were nothing like the medical gloves they had in my previous world, these ones were much thicker and quite unpleasant to put on but it wasn’t really possible not to use it. The ones from my previous world probably had a thickness of around 0.1mm.

It was not easy for me to make the raw rubber a lot thinner without sacrificing the durability. In highly populated areas of the village, there is surely demand for this product as there will be plenty of sick people and this can solve some of the hygiene problems…. Well at least for now, I think that this level of quality is already sufficient.

After that I also managed to prepare protective gear for the back of the hands and wrist it resembled a gauntlet type thing.

Well, although my products were still far from complete, there was nothing that needed rushing, if I asked around for some advice and help, I could probably learn how to create the rim for my tyres and also the wiring to create a better chainmail product. Hegard also managed to gain a little more knowledge about the production and characteristics of rubber, so I’m pretty sure that he would be able to know what materials were needed for certain products and a general idea of how the product is made.

Several months have passed, and the prototypes of certain products have been completed. My void magic has steadily increased in levels, and this has significantly contributed to my ability in shaping and manufacturing products. First I use earth magic and wind magic to build a mould, and it was even possible to create a miniature sized model of certain rubber products.

I did try to make the rim for the tyres, but because I was using earth magic, it wasn’t really made out of metal, and was instead made out of soil. Well, because I couldn’t really make the rim, I decided to ask Hegard for help, but in order to make the metal rim we needed plenty of materials which means more money needed to be spent, moreover we needed to draw up the blueprints as well. Another thing was that the nearest blacksmith was only available in the vicinity of Dorrito town, which was obviously quite far away, and if the creation failed, than it would be really troublesome to get the blacksmith to fix the product.

According to my limited knowledge of this world, all I knew was that dwarfs were a race that specialised in blacksmithing. And if I am not mistaken, I thought that there was a dwarf in Bakkudo village? One of the lesser samurai’s clan was a dwarf clan. I was filled with high hopes and expectations when I asked the dwarf Flintogeru, for help, but he replied “If every single dwarf was a blacksmith specialist, how do you think the dwarfs can plant agricultural crops and brew good alcohol?”

Well I guess that’s true. But the problem is that I’ve never seen a smithing place, and I have never seen a blacksmithing tool. Is my only option to crazily devote myself to magic and find a way to process metal in such a way…..? No, that would be impossible. Considering the pace at which my void magic is going up in levels, if I continued to practice as I have been doing thus far, and let’s not forget that I also have to practice using up my MP in order to increase it, I will take about 4~5 years before I can see tangible results.

The best I can do is put pressurized air into the tyre, aside from that we will have to wait until later. For back-up tyres I made various kinds of tyres, where the inside was purely raw rubber, or where I experimented with the soft rubber or the hard rubber or a mixture of both. After all that experimentation, I did feel as though the overall product had been improved somewhat…. But if you were to ask me, if the products would sell, I wouldn’t be able to say for sure.

I managed to improve the sling shot pretty well, and I managed to combine the main part of the sling shot with the ebonite rubber to increase the toughness. I also improved the handle, so that it was much easier to grasp. In my humbled opinion it has already surpassed the level of a mere toy…

When I tested out its power by aiming at a tree, whilst it may differ slightly from each tree depending on the type of tree it was, I confirmed that it was able to pierce through most types of wood. I also wondered just how much damage it could cause to the protective gear I made with the use of the hard rubber, if I tested it out I could probably figure out the power of my sling shot and how well my gear protected its wearer.

Moreover, I also created a hose about 1~2 cm in diameter using the soft rubber. Whilst there may not be much demand for this product in Bakkudo village, I still thought that in the highly populated areas, they would need something like a siphon as it was generally useful. Another thing was that I made a square cushion from the soft rubber so that we could sit on it. I shaped it like a square cushion from my previous world, and I basically put air on the inside to give it that feeling of soft buoyancy. The rubber was quite thick, so I don’t think that air would leak out of it. If it was covered up in some sort of cloth, I’m sure people will find plenty of uses for it, for example: the driver of the wagons can always use it to sit more comfortably, or it can be wrapped around cargo and used as a sort of protective cushioning etc…

Because of the rim problem, I still could not make the air filled tyres just yet, I continued to steadily improve the design and practicability of the hard rubber used to make the tyre, and also the air tube which was used to keep the pressurized air within the tyres, I basically used and created anything I could come up with.



  1. Thanks for the chapter!
    Rubber industry R&D department established.

  2. Thank ypu very much for the chapter

  3. ndong oto o lionel gilles

    He shouldve starter by coating then wooden ones à bit of history .

  4. The man who’d become king, by producing rubber!

  5. I’m suprised he didn’t just use a wooden rim. Much cheaper, easier, and economical considering the weight the wagons are going to carry. All that’s needed are thicker wheels.

    There’s also handcarts with rubber wheels.

    • exactly my thought. but then again he probably want to make high quality product so it can sell easily. because if a new product defected it will cost him in the long run.

      • I was honestly cursing at him about not thinking of that and jumping straight to modern tires in the 15 Century world

  6. The Rubber Lord ?

  7. well why not air bags as shock absorbers for the wagons.. the Cadillac of wagons!

  8. Thank you very much for the chapter!

  9. why couldn’t he make the rims of the tires out of wood? It would make EVERYTHING so much simpler….

    Thanks so much for all your hard work!!!

  10. He should just ask Luffy for help.

  11. Wow, and he calls himself a salesmen? He lives in a country where people can become stronger by leveling up, without any transport beside horses and said horses are scarce. he has everything to make a bike tyre, but doesn´t think of making a bike as a vehicle xD

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