Super Spamf folding stock. You'll need the original Spamf kit, the Super Spamf kit, and then Telcon's top rail set. One of the rear pieces for the top rail kit is replaced by the adapter piece here- default, it folds to the left. Mirror the adapter and the stock piece to fold to the right.

As far as hardware goes, you'll need four M3x14 screws for the cheek rest and buttplate, and one M3x30 screw and a relatively strong 5 to 7mm wide spring. You'll also need four M3 heat set inserts for the stock- two on top, two on the back, and one in the hinge.

Assembly: get the heat sets in. Cut spring to size, put that in the hole in the top of the adapter piece. Screw cheek rest and buttplate onto the stock. Press down the spring with the stock, slide onto the adapter until the locking lug can be pushed into its recess. Put the M3x30 screw in through the hinge. Don't tighten down all the way, just enough to capture the stock. Now you should be able to push the entire stock down to swing it forwards or backwards.

Remixed in Fusion360