Look up “pocket screw”, you would do this on the backside.
Depending on how much this thing might move you could also get just a flat bracket that bridges one piece to the other. Not sure how you would use a 90 degree bracket on two pieces connected in same plane
vatechtigger t1_j4un65g wrote
Reply to Simplest/cheapest way to attack two pieces wood together at a right angle by Bui1ding
Look up “pocket screw”, you would do this on the backside.
Depending on how much this thing might move you could also get just a flat bracket that bridges one piece to the other. Not sure how you would use a 90 degree bracket on two pieces connected in same plane