US source of Panzerholtz?

Right Teo, you need diamond tooling for this. Rich, far cheaper, easier to get and deal with is solid surface material. I like quartz products best. You can go to installers and get cut offs cheap. Laminate it with a plate of aluminum in between and you'll have a wonderful plinth.  

I did a DIY plinth several years ago and settled on Corian/MDF/Corian.  The MDF was soaked with a very thin 2 part epoxy (Smith Systems Clear Penetrating Epoxy Sealer or CPES), sort of a poor man's Panzerholtz.  The results were quite impressive and very inexpensive to build.

https://www.diyaudio.com/forums/analogue-source/312473-diy-cld-plinth-design-measured-approach.html

I used panzerholz B25 for my DIY TT plinth. Agreed, hard to work with, gummy (the glue) and hard (beech veneer). I did most of the cutting with a jig-saw (German blades) and file, and a diamond hole saw. Takes a good finish.

The thing is, it's acoustically dead, and it epoxies up very nicely, which is important for constrained layer damping. Which Delrin does not (epoxy nicely).

One of the very best go to materials, IMO. Worth the price? Depends on how you value your design time.

How is Paperstone for this application?   It seems to use a similar production process, and it's made in the midwest.   Also goes by the name of Richlite.   It's not cheap, though.   Available in several thicknesses.