I just found this on another site. All pictures are expired, but I think these measurements refer to the one piece template. Google search for treadmarks tail tidy. Oooh, i'm getting itchy to get this done...
"I had a few minutes at work yesterday and decided to knock this out. Was way easy!
The sheet of paper above is standard 8.5" x 11" for size reference. (Donated from our copy machine) Different states/countries have different size tags. After marking the centerline, place your tag on the bottom as shown, then trace around tag and mounting holes.
The distance between the first line from the top, and the second line is 4.7".
The distance between the holes on the top line is 6.7".
The distance between the holes on the second line is 2.8"
I laid out 3/4" washers just to give me an idea where my outside lines would go.
I went with oversize 1.0" washers on the top because these holes need to fit over the mounting posts for the forward mounts.
Use a straight edge and draw lines connecting all of the circle outsides. Add tabs for blinkers of your choice. Stock width was 1.2"
Cut out template, tape it to your material, centerpunch all hole locations, then trace around template with marker.
Rough cutout, with 1/8" pilot holes drilled and bend locations marked.
Smooth out all rough edges with file, use step drill to drill 3/8" holes in all locations, and 3/4" holes at forward mounting points. (I used a hydraulic greenlee hole punch for the big holes, but those are not really needed. They do look pretty spiffy tho!
I used a large vise with wood 2x4s to bend main bend. I also used a cresent wrench to bend blinker tabs. Try to get bends right the first time, as too many adjustments will cause the metal to weaken.
Another option would be to go to your local sheet metal shop and ask them to use a sheet metal brake to make the bends.
Perform a rough fit to locate key lock to suit your preference. Careful not to drill hole too large like I did. File notch in hole to hold key lock so it won't rotate. Mark and drill mounting holes and locating tabs for blinkers of your choice. Mark and drill hole for blinker wires to pass through plate to harness.
It may help to bend forward mounting points up on the sides, because the bottom of the tail section is not really flat.
I used 2 each, pieces of 3/4" heater hose, cut to 1/2" length with large fender washers to pull up the forward mounting points. You may also want to use weatherstrip to form a gasket to better seal out the elements.
Hope this helps 'splain things, and good luck fabbin yer own"
Credit where credit is due: thanks Treadmarks!