Regas and it's variants (Michell, Origin Live, Audiomods,etc) are so common that arm boards are usually pretty easy to source.
What is your table?
For my Townshend Rock and Scheu / Eurolab tables I make my own boards. And I have no shop or fancy tools, just hand tools. But it all depends on how the arm goes on the table. Plates / boards for these tables simply screw onto the plinth so it's not that difficult.
For the Rock I simply bought some pre-cut quarter inch thick acrylic rectangles on EBay, same as the what came on the table. Then just carefully measure mount distance and drill holes for arm and plinth mounting.
For the Scheu the stock plate is a thick 20 mm acrylic circle which I could not source anywhere in the exact diameter.....apart from dealers at rip off prices.
So I just bought some bamboo cutting boards of the same thickness and made what I needed. Bit more work than simply drilling holes on the Rock's rectangular and thinner acrylic, but a jigsaw, palm sander and drill is all that's needed.