If it want to use larger crucibles, I've found a way to do it. Search for "specialty diamond" on eBay. They make the Hardin furnace which essentially is a clone of the Tabletop. You can order their flange.. it does require a little trim around the edges, but pretty easy to install. This will allow you to use their crucibles. All of their crucibles (1kg up to 4kg) are the same diameter. I melt 10oz bars in my 3kg... Hope this helps!