Using Build Your Own Metal Working Shop From Scrap by Dave Gingery, we made and then slightly upgraded an economical wood/propane-fired furnace capable of melting aluminum. We also built simple work tables to hold the oil sand used to make the patterns, and cheap construction material for flask-making. We make our own rammers for packing the sand using the shop's wood lathe.
Patterns can be made with pre-existing positives, found objects, 3D prints, etc. Milling patterns is more setup work but usually makes for much easier packing than creating parting lines by hand. p>
We have access to a lot of water jet scrap, so we're able to just cut good quality aluminum down to pieces that fit into the crucible.
The current setup is propane-burning. In 20-30 minutes the furnace can be brought from outside temperature to the casting temperature range.
Then the crucible is carefully removed and oxides and other floating debris can be skimmed off the top.
This is an Instagram acquaintance of mine who found a beautiful pile of wooden sand casting flasks. A LOT of work went into prepping each of these. Note the channels that the metal flows through all added to the pattern.There's a lot of planning that can be put into the organization of patterns as well as the objects themselves to minimize defects and other casting issues.
Will add to this and other documentation over time