About this 3D model

Print this standing up with a brim around 5mm. The length of this piece is 100mm but you can scale it to whatever size you like in the Z axis to give you the length required. The piece that hangs down at the front is 12mm long, because my printer is sitting on a 12mm MDF board so this is where you would secure the piece. The inside can just sit behind the 2020 unatached and it sits there nicely. I haven't added any holes because most people would scale the length to their liking, so you can just drill holes through it as it's only 1mm thick.