I use Kerax 4600 for my snap bars and my finished bars with this mould measure approx 90mm x 98mm x 10mm and weigh roughly 50gg.
 
Food option available

These moulds can be heated to temperatures up to 200 degrees although I personally recommend around 100 degrees. Warming your moulds can help give a smoother, shinier finish to your bars although some pitting can still occur