CAD file available on OnShape: https://cad.onshape.com/documents/247bc438b6ceab3094eaa63c/w/3158f89acecb50286f3e013c/e/e68e1e9563f474808e061051

• Start with a piece of MDF at least 33.75"x14.5"
  
• Adjust hole sizes and depths appropriately (you will need to do this for your setup). Make sure that the holes for the threaded inserts go all the way through the wood (they don't in the attached *.c2d files, and all had to have the final thin piece drilled out by hand).
  
  
  
  There are 3 files for this. I recommend cutting them in order (AFTER:
  
• sacrificial wasteboard cuts:
  
  • All of the cuts for the new sacrificial wasteboard.
    
  • Stick your MDF along the front edge of your factory wasteboard, leaving a bit poking off left and right of the maximum (I used carpet tape, but masking+superglue works fine).
    
  • Once the cut is done, remove the MDF and trim off the excess on a table saw (or whatever).
    
• factory wasteboard cuts:
  
  • This cuts holes in the factory wasteboard for the eight 3/8" threaded inserts.
    
  • Run this after removing the new wasteboard but ideally before turning the machine off, so you know the holes will all line up properly.
    
• wasteboard:
  
  • I should have named this "wasteboard surfacing". It's designed for a 1" surfacing bit.
    
    
    
    Additional Parts:
    
• about 96" Rockler T-track (widths/depths might need to be adjusted for other brands) and small screws for attaching it.
  
• 98 x 1/4-20 threaded inserts (I used brass EZ Lok 400-4, https://www.ezlok.com/ezknife-insert-400-4, because the zinc ones are really inconsistent -- in retrospect, these ones don't go into the MDF any straighter so they may not have been worth the extra cost).
  
• 8 x 3/8-16 threaded inserts (no reason other than these are the same size used for beer tap handles and I had them on hand).
  
• 1" long 3/8-16 bolts/washers to attach to factory wasteboard.