Lockblock - printable connector

Many puzzle pieces have complex shapes with inevitable overhangs whichever way you orient them. I would like to try soluble support material but I don't yet have dual extruder printing capability. Ordinary support material leaves nasty marks on the downward-facing surfaces.

My latest idea was to split the piece horizontally through the middle and print the two halves facing upwards with a custom connecting joint on top of each piece. The joint consists of a triangular peg next to a triangular