The piece is sculpted with Plasticine and cast from fiberglass resin. These are not the best mateials to use but they are cheap and get the job done.
I was inspired by Sylvia's Super Awesome Show, she made it look easy.
Step 1: What You Need
Plasticine (oil clay)is used for making the master shape. Real Plasticine is meant to melt hen it gets to about 100C which would make it easy to get out of the mold. Unfortunately mine was a knock off that just caught fire.
Plaster of Paris is for making the mold. you pour it around the Plasticine sculpture.
Not pictured is Lego, for making a box, and plastic wrap or aluminium foil for lining the box.
Step 2: Make the Piece
I rolled the clay flat an trimed the excess. Then I made a right angle shape. In the join i added a small sausage to make sure there was proper contact between the pieces. I did not want a mold with gaps.
I cut out a small cylinder and attached it to the top. This created an overhang in the mold that gave me trouble later.
Since i was trying to create a right angle I molded it onto the corner of the kitchen counter.
Cutting the clay is much easier if your tools are lightly oiled.
Step 3: Make the Mold
Line the box/bowl with plastic wrap as this will make it easier to remove. It will also make a Lego box waterproof and keep it clean. I had a problem getting the wrap into the box and this shows in the mold. It is best if you find a way to hold the wrap down.
To mix the plaster of paris measure how much water it takes to fill the box, that is how much water you should use. Add the plaster to the water a bit at a time and stir until it forms little islands. it should be the consistency of thick paint.
Because I knew i couldn't melt the clay out of the mold I put two tooth picks halfway up the piece so that i could cut the mold in half later. Not pictured I pushed one pick right through and left it there, this caused problems.
Place the piece in the box, as centrally as possibly. Mine was off centre so the mold wall was very thin in some places. Now pour in the plaster. You should do this entire step outside or some where that can get messy, not the kitchen.
Plaster of Paris mixed with water forms a chemical reaction that makes it hard, it doesn't just dry out like clay. This means that if it hardens on you counter or floor you have yo chip it away with a chisel. Think cement. By the same token, don't throw excess plaster down the drain it will harden under water and block you pipes.
Step 4: Extract the Mold
Take apart the lego box and peel away the plastic wrap. Where the plastic wrap didn't get into the corners of the box the mold had rounded edges, this weakened it and made the next step harder. Try to do better than me.
Step 5: Getting the Plasticine Out
Once I had cut all the way around I gave it a gentle pull and it cam apart. From the picture you can see how off centre I was.
I dunked the porous mold into water hoping that a wet mold would make getting the Plasticine out easier.
Use a piece of wire or a small tool to scrape out the clay. Be careful not to damage the mold though. Since the Plasticine piece was resting on the bottom of the box there was a hole in the bottom of the mold. I broke one half in two and the other half had a hole in it where the wall was thin.
In the last picture you can see the embedded tooth pick.
Step 6: Resin Casting.
Since the Plasticine piece was resting on the bottom of the box there was a hole in the bottom of the mold. I used this hole to pour the resin in.
Before putting in all the pieces spray them with a release agent, in this case: cooking spray. a friend suggested spraying with hair spray to seal the plaster and then the release. I shall try this next time.
Again I lined the box with plastic to stop sticking and mess. This was a mistake. The solvent in the resin soaked through the plastic and started eating into the lego, as in the last pic. In the future i will use aluminium foil.
I mixed 25ml of resin with five drops of hardener in a disposable cup. It took hours to cure so i think i need more hardener. 25ml was too much so i made a poor mold of a lego brick as well.
Using resin is an outside job. It will make a mess a a chissel wont help this time. It also gives off fumes that a better left outside.
Step 7: Remove the Casting From the Mold.
Once I had removed all the mold i left it in the sun a bit longer.
The second picture shows what it looked like once it was hard.
Step 8: Result!
A flaw in the casting also made the stub only semi circular.
I am really encouraged by these results and my next attempt will be better.
Thanks for reading, please comment if you have any questions or help.