I was out of t-nuts and square nuts... This is the result. Supports are built in and need removed (see post processing). Easily removable should you need to access the stepper pulley. Based off of peaberry's "Kossel Linear Drive Belt Lower Cover".
You have to remove the built in supports with a knife, BE CAREFUL! Always cut away from yourself and body parts. If the bolt will not rotate inside the extrusion be careful not to force it, you can shear the bolt in two. Use a file or pocket knife if necessary to clean up the bearing surface of the t-nut.