I have hand made some from stock aluminum sheet tracing the one I had pre turret, and they worked well for a year or so before the right propper units came along. Cut with tin snips, drilled and filed. Lens threads where put though the hole and self amalgamating tape wrapped around to hold the lens in the mount. Black 4 ply matt board shimmed the boards off the turret so the back of the lens sat clear and the turret could then turn.