ISTM that some very accurate drilling is needed, beyond the capabilities of “hand tools” (in my hands, at least). I assume a decent drill press would do it if you make a jig to hold the nylon bolt.
I thought that the nylon bolt idea was absolutely brilliant and it is a great pity that this simple and elegant design was discontinued. SOTABEAMS no longer sells SOTA beams I am surprised that it wasn’t commercially viable to continue it, even if sales volumes were modest. The materials cost seemed very small. Once the cutting and drilling jigs are made I would have expected it to be pretty easy to put together, and the final assembly was always left to the customer.
My SB270 isn’t used as much as it should be, but I’m not parting with it.