As well as turning l am a drummer and both of these have come together with me making custom snare drums. Custom drum making is more prominent in the USA than the UK and the most up to date information is available from the USA custom drum suppliers. Defining what you mean by custom drums is a great discussion, in my mind if you buy in a blank ply shell as your starting point it is not a custom drum more like a DIY kit for a drum, especially if you purchase it with the holes drilled and bearing edges completed.
The snare drums I make are from solid oak
Solid Oak 
oak carved and coloured 
Green blank 
Do-nut ready for drying 
starting to finish 
finished blank 
adding the fittings and bearing edge