I didn't make it, but here's a convenient photo I have, under full sail with a 3-strand nylon helmsman. It was pretty home-made looking: mounted to blocks of plastic that were through-bolted (single bolt) on big blobs of sealant to sit flat, the feet attached with 4 small screws each, and and the rail sat in the feet/ help by setscrews
As a side note, I just set the mast on the railing to trailer the boat. However, I think I had a tendancy to pull it down a wee too tight with the ratchet straps..the slight bend in the middle is my addition.