Alright, let’s make a mold. This one is Marilyn Monroe . We can make a one or two part mold. In this case, the easiest to make is the one part mold. This means when we are finished we will be casting a head by pouring the resin in the one hole in the mold.

Initially you will need to find a container to hold both the item to be molded and the compound together until it cures. Molding compounds can cure in anywhere form 1/2 hour to 24 hours, depending on their properties.

Mixing ratios are also a factor to contend with. Without proper scales and measuring equipment it can be difficult. As a beginner, it is best to use something that works in a 1:1 ratio or 50%-50% mix. It will be a lot easier to handle.

A good tip for a container is using Lego. You can re-use it time and again, the rubber doesn’t stick it and it can be made it almost any shape. For a bottom on the container, the Klean Clay (or plastercyne) comes in handy. Make a flattened piece at least 1/4” thick that will cover the entire opening on the bottom of the box. Press the lego box into the Klean Clay base. It will sink a bit and this will keep the liquid molding compound from leaking out.

The box size is arrived at by making a box at least 1/4” larger than the head. We are going to hang the head down into the box and hold it centered in the middle. This is done by using a rod (or doweling) that will span the box and hold the neck base level with top lip of the box. I like to put a little clay into the neck and attach it to the middle of the rod.
You’ll need a mixing cup, mixing stick, gloves and eye protection. Work in good light on a surface that can get dripped on without problem like cardboard.

When mixing any molding compound it is essential to get all bubbles out of the mix before pouring into mold. Try not to create too many air pocket bubbles by stirring slowly and trying not to ‘fold’ while you stir. Next you can repeatedly ‘tap’ the container to dislodge bubbles and bring them to the surface of the mixture. Better yet, hold the mixture on a dryer or vacuum cleaner and the vibration will drive bubbles up.

When pouring into mold box pour in a thin, slow stream. This way any other bubbles will burst on their way out of the cup. Pour slowly onto the lowest part of the mold and continue in the same spot allowing the compound the slowly (and I mean slowly) envelope the head being molded. The longer the molding compound take to cure, the more time for any bubble to rise—and not be found clinging on the nose of your final mold!

Allow to cure. Now we need to get the head out of the mold. In this case, being a one-part mold, we simple slit down the back of the mold with an exacto knife, just enough to release it (not too far since it needs to hold resin later when we cast) and out pops the head.

You got yourself a simple one part mold!