2-way 2020 extrusoin corner connector

I was looking for a way to make a frame using 2020 aluminum extrusoin.  I wanted to have the inside track corners to be open to accept a plexiglass sheet.  I searched for a  connector, but only found a 3-way corner connector, or a cube connector, so I decided to design a 2-way connector.   

Notes:

1. The connection is designed to be snug to keep parts together.  I used a clamp to press joint together.
2. Despite the snug fit, I found the single prong was still too loose, so I added the two holes in the single prong connector.  The holes are designed with a countersink to use with a M3x4 cap head screw.