How to Make Your Own Papercrete Coasters

In this instructable we'll teach you how to make your own press and mold to make papercrete coasters. "What's papercrete?" you may ask. Well, it's a building material made from a mixture of paper, water and cement. It may not be as strong as regular concrete but it's a lot lighter and it absorbs heat pretty well. That makes these coasters an ideal way to get rid of used paper, newspapers, magazines, ...

step 1 to 3 - The press
step 4 to 5 - The mold
step 6 - Papercrete

Tools for the assembly

- Drill
- Drill bits for metal (M8)
- Drill bits for wood (M6, small ones for predrilling the holes for screws
- Angle grinder and cut-off discs for steel
- Lasercutter or CNC
- Table saw or track saw
- Center punch and hammer
- Clamps
- Hand saw
- Sandpaper
- Measuring tape
- Pencils for marking out the holes
- Wrenches (M6, M8)
- Wood glue

Parts for the papercrete tool

- 4 Industrial brackets (galvanized) 150 x 250 x 20mm (looks similar to this)
- 1 Threaded rod M8 x 1000mm
- 1 Aluminium tube profile 10 x 1000mm
- 2 Flat steel profiles 30 x 2 x 1000mm
- 1 Multiplex sheet 10mm
- 16 Nuts M8
- 8 Bolts M6 30mm
- 1 Hardwood (beech, walnut, oak, ...)
- 1 Formply sheet 18mm
- 7 Small Screws
- 16 Screws 30mm
- 1 Dowel M6 x 1000mm
- 1 Construction angle (galvanized) 100 x 70 x 30 (looks similar to this)
- 8 Spring lock washers M8
- 1 Paint mixer 85 mm (this one)

Materials for the papercrete

- Paper, newspaper, magazines, ...
- Cement
- Water
- Food coloring (optional)

Here you'll find an overview of all the materials you'll need to cut to size.

Steel profiles

Cut the steel profiles to size, drill the holes and bend the handle.

You'll find the exact dimensions in the technical drawings below.

threaded rods

Make three pieces that are 240mm long and one that is 210mm long

Multiplex

Make a piece of plywood of 200 x 200mm. the thickness doesn't really matter but this piece of wood will have to endure some force so we recommend at least 10mm.

The formply needs to be 600 x 1200mm. We'll bolt the press to this piece and you can also use it as a workstation. If you don't mind getting your table or floor dirty you can also make this piece smaller to only fit the press. Make some extra stips from the scrap formply. These will be used as little legs for the workstation.

You'll find the dimensions for the holes in the files below.

Galvanized brackets

The long side of the largest brackets need to be a little shorter to save some space.

The smaller brackets need some modification as well. You need to make an extra hole with your M8 drill bit on the short side of the brackets. Try to make the holes at the same spot on the brackets to make the later alignment easier. One of the brackets also needs to be shortened on the long side to make both of the brackets fit on the 200 x 200mm piece of plywood.

Hardwood

Cut a 20 x 30 x 130mm piece of hardwood to size. This will be used as a handle so you can give it any shape you want, but keep one of the long sides flat so you can attach it to the steel part of the handle. Sand the wood up to 320 grit and finish it with wood oil to give it a nice look and feel.

Screw the small brackets on the 200 x 200mm plywood as seen on the pictures. Do the same for the hardwood handle. You can now put all of this together with the long steel profiles and 2 of the long threaded rods. Don't forget to add a lockring and nuts on both sides! The order is nut, lockring, steel profile, nut. Also add some aluminium tubing on both of the threaded rods. They will function as spacers.

First you have to make a aluminium tube to fit over the small threaded rod. Then you have to bolt the rod to the two large brackets that will be closest together. This may be a little tricky. For now only put the inside nuts on the rod. We'll add the lockring and the other nuts later. Do the same with the remaining larger rod. This one doesn't need a aluminium tube. Now that these are ready you can bolt the large brackets to the forply sheet.

Now all that's left to do is bolt the previous assembly to the large brackets. He're you'll have to add the lockring and the nuts. The handle sits ont the side where the brackets are closest together.

Your press is finished!

Plywood

Take the 10mm plywood and cut it to 600 x 450mm. This is the max size of the lasercutter that we could use so you may need to change it a bit to fit your lasercutter. If you're using a CNC this probably won't be necessary.

You'll find the lasercut file with some different shaped coasters below, you can easily modify the file and add your own shapes.

Dowels

You need four dowels to make the mold. We made our dowels 100mm long but if your mold doesn't need to be as high you can make them shorter. Our dowels were cut a bit too long so we could cut them flush to the top plate later.

First, grab six (or how many you need) of the leg pieces. We're going to glue them together and align them with dowels. Don't glue all six of them together at once but work one by one. You have to do this twice but make sure that the dowels don't stick out at the same end or else the parts won't fit together anymore. Use a couple of clamps to clamp the legs together and let them dry.

When the legs are dry you can glue the top piece with all the holes to the legs. Now all that's left to do is trim the dowels and you mold is ready!

As we said previously, papercrete is a mixture of paper, cement and water. There's isn't a set recipe so you can experiment as much as you want with the ingredients or look online but we'll give you the proportions that we used.

To make one big coaster you need around 100g of shredded paper and 100g of cement. First you need to make a pulp of the paper with water. The amount of water doesn't really matter because you can pour the excess out. After you have a pulp and poured the excess out you can add the cement and mix it through. Now you can put the papercrete in the mold and you can press it. Don't press too hard because the water you press out will also contain some cement.

Tip! Place a towel or some kind of container under the mold to catch the water.

After 20 minutes you can try and take the coaster out of the mold. Be careful because it can still break! Place it somewhere to dry for 24 hours (or longer).