UPDATE: Based on Deviant's advice I realigned the pegs therefore the picture of the printed part does not correctly represent the model.
A 3d printable clam for casting keys. I made it for mainly dimple keys as those are the most common keys where I live.
Watch Deviant Ollam explain key casting here:
The holder is only to keep the clam in the correct orientation when molding. It will not hold the pieces together firmly enough.
I would not use anything flexible or with low melting point.