FDM Printed pattern to make a silicone mould. It has a few coats of interior enamel paint to cover up print artefacts.
The mould on the right is silicone. I have just cast the refractory mould on the left. It will go into the kiln to receive the glass.
A very poorly thought out system of supporting the clay funnel resulted in a cracked casting. One of the bits of shelf used to support the funnel was entrapped in the casting, causing the glass to crack as it shrank around it.
A closeup look at the surface of the casting that was in contact with the mould.
A ceramic support that keys into the cells on the underside of the blank will hold it securely as the glass softens and stretches under its own weight at 650 C.
The top surface has been ground off using 500 mesh abrasive. It will polish in the fire as the glass softens and stretches down.