I still haven't set-up my 3D printer so I haven't printed and tried this but I am pretty satisfied that it should work very well. I'm looking forward to setting up my printer and printing some of these so I can get my TRX-4 kit trail worthy without having to glue the stock rims.
You'll need to print 6 of these for each rim & get a M3x10 screw for each. I'm going to be using the 2 preexisting air holes so I'll only need to drill 4 additional wholes, though, the 2 air whole are going to need to be widened to accommodate the 3mm screws.
Also, if you don't have a 3D printer let me know & I might be able to print them and mail them to you for a small fee.