HDPE is the plastic that you’ll be able to make in Mekanism, and it starts out as small pellets that come out of the 
Pressurized Reaction Chamber. To make them, you’ll need a 
Substrate, some Liquid Ethene and a little bit of Oxygen, and the pellets can then be pressed into sheets or crafted into rods, with the sheets being the ones that you’ll need the most of.
You won’t need any of it until quite late on, as it’s used to make the MekaSuit, the 
Meka-Tool and the modules that go into both of them. By that point, you’ll usually have some Ethene (called Ethylene in older versions) being made as a fuel already, so the plastic is able to come from the same machines.
How to Get It
HDPE Pellets
An 
HDPE Pellet is made in the Pressurized Reaction Chamber, which uses all three of its inputs for this. You’ll need one Substrate in the item slot, 50 mB of Liquid Ethene in the fluid tank and 10 mB of Oxygen in the chemical tank. Each one takes 3 seconds, but the machine will draw 402 FE/t (1,005 J/t) while it’s working, which is far more than usual.
The recipe above only shows the item that goes in, so remember that the other two are needed as well. The Ethene also has to be a liquid for this, whereas it comes out as a chemical when it’s made. So you’ll want to send it through a 
Rotary Condensentrator first, which is able to turn it into a liquid when it’s set to the right mode.
This machine is only able to hold 800 FE at a time, and it won’t start working unless it has enough stored to cover what it needs. With this recipe, a second 
Speed Upgrade should push the cost past that in our reading of the code, so it’d just sit there. Add some 
Energy Upgrades alongside them, as these will make it able to store more.
Substrate, Ethene and Oxygen
All three of the ingredients are able to come from the same place, which starts with 
Bio Fuel, Water and Hydrogen going into another one of these machines. That will give you one Substrate and 100 mB of Ethene each time, so there’s enough Ethene for two pellets but only enough Substrate for one of them. You’ll find how to set all of that up on the Ethene page.
To make up the difference, the same machine is able to multiply your Substrate, as putting one of them in with 200 mB of Water and 100 mB of Ethene will turn it into eight. It’ll give you back 10 mB of Oxygen as well, which happens to be what one pellet needs, though most of it is going to come from an 
Electrolytic Separator instead.
HDPE Sheets, Rods and PlaSticks
An 
HDPE Sheet is made by putting three of the pellets through an 
Enrichment Chamber, and it’s the one that you’ll want to make the most of. The 
HDPE Rod is crafted by hand instead, from four of them in a square, and if you put two rods on top of each other, they’ll make a 
PlaStick.
HDPE Sheet Line
3
The last of those isn’t used in any of the mod’s own recipes, so there isn’t a reason to craft one, unless there’s another mod in your pack that asks for a plastic rod. The rods aren’t used for much either, as the only machine that needs them is the 
Pigment Mixer, and it only takes two of them.
How to Use It
Nearly all of your sheets are going to end up in the gear that you’ll make near the end of the mod, and most of those recipes are going to need 
Polonium Pellets as well. So you won’t be able to craft any of it until you have a Fission Reactor that’s making waste, even if the plastic has been ready for a long time before that.
| Made With Them | HDPE Sheets |
|---|---|
| MekaSuit Helmet, Bodyarmor, Pants and Boots | 4 each |
| Meka-Tool | 2 |
| Modification Station | 4 |
| SPS Casing | 4 each |
| HDPE Reinforced Elytra | 5 |
| Module Base (makes 2) | 1 |
| Energy Unit and ten of the other basic modules | 3 each |
| Solar Neutron Activator | 1 |
The MekaSuit is the first thing that’ll use a lot of it, as you’ll need sixteen sheets for the full set, and the 
Modification Station that’s used to add modules to it takes another four. The SPS needs a lot more than that though, as every piece of its casing takes four sheets, and it’s built out of well over a hundred of them.
HDPE Reinforced Elytra
The 
HDPE Reinforced Elytra is crafted from a normal 
Elytra, with five sheets and two 
Atomic Alloys placed around it. It’s going to work in just the same way as the one you started with, but it has 648 durability instead of 432, and you’re able to repair it with more sheets in an 
Anvil.
It’s also what the 
Elytra Unit is crafted from, so you’ll need to make one of these even if you never plan on wearing it. That’s the module that lets you glide while you’re wearing the MekaSuit, without having to give up the chest slot, and you’ll find it on the MekaSuit and Meka-Tool Modules page.
How Much You Will Need
Each sheet is made from three pellets, and each one of those needs a Substrate, 50 mB of Liquid Ethene and 10 mB of Oxygen. The table below has that worked out for the things that you’re most likely to want to craft first, and it shows that the plastic for a full set of gear doesn’t come to very much at all.
| Crafting | Sheets | Pellets | Liquid Ethene | Oxygen |
|---|---|---|---|---|
| Full MekaSuit | 16 | 48 | 2,400 mB | 480 mB |
| Meka-Tool | 2 | 6 | 300 mB | 60 mB |
| Modification Station | 4 | 12 | 600 mB | 120 mB |
| All three | 22 | 66 | 3,300 mB | 660 mB |
So a single machine is able to get through all of it in a little over three minutes, as long as you’re keeping it supplied with everything. It’s the modules and the SPS that are going to keep it busy after that, and once you have the sheets ready, the next thing to craft with them is the MekaSuit.
FAQ
HDPE Sheets are made by putting three HDPE Pellets through an Enrichment Chamber. The pellets come from the Pressurized Reaction Chamber, which needs a Substrate, 50 mB of Liquid Ethene and 10 mB of Oxygen for each one, so you’ll need an Ethene setup running before you’re able to make any.
It’s usually because the Ethene is going in as a chemical, when this recipe needs it as a liquid, so it has to go through a Rotary Condensentrator first. The other common cause is Speed Upgrades, as two of them should push the power cost above what the machine is able to store, unless it has Energy Upgrades as well.
The PlaStick isn’t used in any recipe in Mekanism, so it doesn’t do anything on its own. It’s tagged as a plastic rod, which means another mod in your pack might be able to use it in place of its own, but otherwise you can leave it alone and keep your pellets for sheets.
It flies in exactly the same way, with the difference being that it has 648 durability, whereas a normal Elytra has 432. It can be repaired with HDPE Sheets as well, which are a lot easier to get than 
Phantom Membranes once the plastic is automated, and it’s needed to craft the Elytra Unit.
