Internal Pistol grip for 4 inch pipe

I am in the middle of a Protomen cosplay build. For the arm-cannon i am using a 4 inch pvc T-junction pipe. I needed a pistol grip that could house a couple of trigger buttons and I needed it to fit inside the pipe, as my arm is going inside the cannon.

This grip is designed to go inside a 4 inch pipe flush with the 'top' of the pipe. there are 4 bolt holes so you can drill thru the pipe and bolt the grip to the pipe very securely. The holes in the grip are designed for round buttons or switches with 16mm threads, and there is a channel to the bottom of the grip for wires.

The 'roof' of the grip is 7mm thick and should be strong enough provided your piece is not super-heavy. the roof is shaped to fit snugly against the inside of a 4 inch pipe. if you do not want to drill holes in your pipe you can choose to just glue the roof to the pipe. I included bolt holes so if maintenance is needed on the grip I can easily take it apart without needed to break apart glue.