We have had several versions of the cabinets and filters.
The first hundred or so were made without any commercial objective of profit whatsoever and we had the crossover made on the fly (see photo in previous post) and the internal faces of the cabinet were lined with bitumen for added neutrality. We even had a very limited series finished in piano lacquer (8 coats with resanding in between coats) which we sold for about 4 times the price of the standard ones (see photos of my daughter's system below featuring a pair of them, together with MY Rega and a A60 amp from A&R Cambridge, now Arcam)
BTW, I bought myself a NAD turntable for Christmas. They are obviously made by REGA, but with a cheaper mindset, and on a positive note the new Rega 251 arm and Ortofon OM5E cartridge, an improvement on the Grado I use on the Rega.
Under commercial pressure, later versions were not lined with bitumen and the filter was later built on a printed circuit board. Although it does not seem to affect the quality of the sound too much, I am still to do an A/B listening test to make sure.
My next project is actually to build new filters on air core inductors, better capacitors (all from Solen...after all they are a French company!) and also implement an impedance compensation network on the midrange driver, and no PCB. There is also room for improvement with the damping cloth used inside the cabinet. I will keep you posted on these experiments.