Hello and welcome to my 2nd Instructable.
I have found myself in need of a large gauge, large diameter non metallic ring to retain a body piercing I have whilst going for an M.R.I scan. I'm almost sure I will have no real need to wear this plastic replacement but I have never had an M.R.I before and I have no idea how long it will take etc so I have decided to attempt to cast a copy of my usual jewellery and this is how I got on.
Step 1: Making a Ring Mould - Hmmm?!?!?
Ok - I'm going to need a few disposable bits and see what is available in my local area, being in England the first stop is Poundland (this for those that really can't guess is a budget shop where all sorts of treasure can be found for just one piece of goldy looking metal). I bought some plastic shot glass sized cups and a tube of two part epoxy. I already had a tub of Composimold that I bought at a cake making fair years earlier and had never tried using it so I thought I'd give it a try as there really wasn't much available locally in that respect.
Step 2: First Go.
I had a think and decided to stick a bit of plasticine in the bottom of one of the cups and dig the ring into it and have it so I could fill the ring from the top of the mould when set and this worked reasonably well. I did get a fairly respectable cast but I found doing it like this made it difficult to remove the original from the mould and I had to destroy the mould to remove the cast.
Step 3: Round Two -
Ok so after playing with the cast epoxy ring I had successfully made I discovered that the Poundland two part epoxy is extremely brittle when fully set and I broke it. I decided to rethink the mould design and try to get the stiff but flexible Composimold to work with me and here is what I came up with. I wrapped a piece of cardboard around the bottom of an upturned plastic shot glass then I rolled a very thin and short length of plasticine and made 3 tiny legs for my ring to sit up on and placed it inside the cardboard tube after placing a battery to create a void in the center I then gave it a glancing spray with WD40, heated up the Composimold and filled it up and placed it into the freezer.
Step 4: Injecting the Epoxy.
Ok so there I am with my ring embedded in the Composimold, I used a craft knife to cut the mould right on the edge of the ring and gently manipulated the ring through the mould pushing the mould into the void left by the battery I had placed in the center of the casting then when it was free from the mould I used a tooth pic to remove the plasticine foot from the edge of the ring. I then mixed the same epoxy and used a child's medicine syringe to suck up the liquid epoxy and inject it into the mould, the beauty of using the near transparent moulding gel was I could see the epoxy flowing round the mould. after letting it set for a few hours I liberated it from the mould and cleaned it up and trimmed the excess plastic away and I'm very pleased with the result, I'm not sure I'm going to trust putting this extremely brittle and practically unknown plastic in my very personal pierced place but if I find a similar but more trusted plastic to use I will at least have a good idea of how to go about it. I did buy a tube of Gorilla brand epoxy and I have A.B.S plastic so I may try an Instructable and make an injection mould for the A.B.S next time, I have a few weeks until my scan so I may have time!
Step 5: Almost Forgot
The materials I used were:
Composimold reusable mould making gel.
Cheap disposable plastic shot glasses.
WD40 (mould release agent).
Extremely cheap 2 part epoxy (composition unstated on the packaging).