Lonnie, here's the process I used for making the floating nut plate t@bs. I typically made a couple dozen in a batch, well over a hundred total.
Start with a length of 16g. cold rolled steel 1.5" wide.
Mark t@b cut lines every 1", allowing for the saw kerf. Don't cut t@bs off yet.
Mark a center line the length of the steel.
Drill center holes with a #19 drill. Mine are 3/8" down from the top of each 1" t@b.
Drill rivet holes with a #41 drill bit, using the template/tool as a drill guide. I typically did all of one side, then flipped the tool over and did all of the other side. Note: The #19 and #41 holes may need to be "reamed" with a drill bit for the template/tool to insert smoothly.
Open the center holes to 13/64". This allows for the 'floating" of the nut plates.
Countersink the rivet holes with a 120* counter sink. Note: After countersinking, the rivet holes may need to be "reamed" for the rivets to insert cleanly.
Rivet the nut plates in place. Note: Don't fully "pull" the first rivet before fitting the second rivet in each nut plate.
Cut the t@bs off using a horizontal band saw.
Using a bench-top belt sander, smooth the edges of the t@bs and round top corners to 1/4"R.
Have fun!
For attaching the panels, after welding the t@bs to the chassis mark the hole to be drilled through the screw hole onto the panel back side with a sharp point. Drill panel to 11/64".