In this puzzle, the 8 pieces form a square grid with 4 parallel pieces crossing the other 4 at right angles. There are two connector types: vertical paired bumps with horizontal paired holes, and horizontal bumps with vertical holes. What's special about this puzzle is that each connector type matches the *same* type. (It is relatively common to see puzzles with two types of connectors where opposite types match.)
There are 10 different pieces possible in this scheme. In this puzzle all are used except the two pieces with all connectors of the same type.
I'm still prototyping this, but I plan on offering it for sale once I have a successful prototype.