Just a note on how I use my still... I use a 30L boiler (like a large electric urn) for turning my yeasty wash into 93-95% alcohol. From about 25L I get 3.5L of spirit (costs under $5 in consumables). I then use a smaller, double-boiler that I made out of a 10L urn and commercial bain-marie insert - it was a bit of a
mission as you need an air-tight set-up or you'll lose the spirit out of anywhere that leaks.
I had to cut a hole in the lid of the bain-marie insert that fit my still, and then get an o-ring/pressure boiler seal to the lid, plus some clamps to hold the lid on tightly. It works really well but took more to set up than I first thought it would (was hoping to just use the urn "as is").
Also, not sure what other people's stills are like, but mine has copper/stainless steel scrubbers inside it which are required for the first part of the process (wash to alcohol), but are removed for the second part (RSO).