The file has 4 copies of the lid, 81mm 2x81.5mm and an 82mm version.
I found the 81.5mm diameter lid did the trick, though I modified the 'design' (i have to lol at that) to make an 82mm version as well.
Use the holes from the main axle hole as handles for the two lids.
a small piece of double sided tape did the job to attach them.
I used 6mm acrylic (NZ stock) however would like to have used 9mm for the extra weight (US stock)
Bean vs Burr in action: