About this 3D model

I created this to attach my standard US mailbox to the top of a fence post. The mail box has a small piece of wood on the underside, so this adapter would be fasted to that wood on the underside of the mailbox and then fitted on the fence post. I squared off the chamfered edges from the top of my fence post for a better fit. 3.56 in. x 3.56 in. are actual 4x4 dimensions ;P. This model is 92mmx92mm (3.62inx3.62in) on the inside.