Search too for "tubalcain foundry videos" He talks a lot of sense.
Can't comment on sizes. It depends on what size castings you want to make. I cast handbells - I need around 50mm between the pattern and the side of my (wooden) moulds - and around that depth top and bottom (this for a 100mm diameter bell).
Choose your mould sand. If it is something small and detailed, you'll need oil-based sand. Otherwise standard green sand* is fine. I've experimented with home-made sand with fine silver sand from the builders merchant and Fuller's Earth (ie cat litter), but, with all the time and effort you'll spend, go get some proper stuff!
* It's actually bright red!
Aluminium is relatively easy to pour. Brass is a bit gloopier - you need to pay more attention to the sprue - and making a bottom-entry channel is better. Bell metal is a pig to pour - and tends to mess up your crucible big time!
What are you using as a furnace? There are quite a lot of VERY significant safety issues there. DON'T get over-enthused by a number of those gung-ho American (usually) self-build furnaces! Be careful!
If you are new to all this, can I recommend Art and Emma?
Artisan Foundry Shop He knows his stuff, runs really helpful courses and sells materials in sane quantities.
