"Roger Hayter" wrote in message
...

It is certainly something to bear in mind when designing circuits for
above 10GHz. My rule of thumb is 'use PTFE', but I have no scientific
justification for that!

My enquiry relates to PolyLactic Acid (PLA) which is what my 3D printer
extrudes, because I wish to use it to produce some insulator blocks for
the HRO-like Catacomb band switching in my "Vapourware" Retro RX.