Twinlock Desk Tray - Replacement Risers

I have 9 of these Twinlock desk trays in my study (https://www.takealot.com/twinlock-desk-tray-red-2-trays-and-4-risers/PLID28028793), however the risers that came with them are at best *very flimsy* and the trays are not very solid/sturdy once you start filling them up with paperwork.

The set of two trays also only comes with 4 risers, so you are limited to two stacked trays only - I wanted 3 stacked trays to fit my shelf spacing, so I designed these risers to allow me to do this; although p