I made this at TechShop Detroit (www.techshop.ws).
Step 1: Cut Metal Flat Bar into Squares
Step 2: Grind Edges to a Smooth Finish
Step 3: Drill Hole into Squares
A 1/8" hole is the perfect size to fit in an old-fashioned coat hanger. Use a drill press and make sure you have the correct speed for steel. Change the speed on the drill press if necessary.
Step 4: Prepare Squares for Powder Coating
First, sandblast the material as shown in How to Use a Sand Blaster.
Then soak your parts in a TSP bath as shown in Using TSP to Prepare Parts for Powder Coating.
Lastly, hang and clean your parts with Acetone as shown in Using Acetone to Prepare Parts for Power Coating.