I needed cross members for my car rack.  So I made some.  It's designed to hold a ½ piece of EMT as the cross bar.  The EMT is a TIGHT fit, but it fits and is very secure.  I printed the bottom part of the bracket at 100% infill laid on its side, because it takes most of the stress of the bolts.  The top part I printed at 50% infill, and it's super sturdy.  

Both parts I printed with PETG so it will withstand the heat of being on top of a car.  But Its winter where I am, and its holding up just fine with the cold.    

It could easily be modified to hold something other than a piece of pipe as well.  I just have an abundance of EMT.