How permanent do you want this solution to be? I prototype tube circuits using wood and copper plated nails, a method that pre-dates me by easily 40 years, and for that it's great, but I can't say I'd want that inside my amp day in/day out.
Also, typical plastics will melt when you heat up the bolt to solder in the component. I'd probably go the extra bit of effort and get the right materials/use commonly accepted ways of doing this sort of stuff.
If you want turret board material, it's called G10. If you want copper clad board for circuit boards, you're looking for copper clad FR4. G10 can be purchased from specialty dealers, or "generic" places like McMaster Carr. Copper clad FR4 can also be found at specialty places, or the big electronic retailers like Mouser, Digikey, Newark, Allied, Jamco, etc.
If this is a small project, perf board can be purchased at RadioShack, or you can buy strip board (vero board) from the big electronic retailers.