[time-nuts] Thermal insulation choice?

[Malcolm]

I would recommend and have used 1/4 inch polystyrene foam that is available in roll form from DIY stores and either glue or double sided tape.  It is easily workable and cheap and achieves what you want.  There is a caveat in that you should also use nylon or other (heat) insulating washers and nylon nuts and bolts to attach the oven to the case.  Otherwise you will loose heat through conduction and introduce cold spots to the oven

Regards

Malcolm