A divider for drawers on the Draper Expert 89470 30-Drawer Storage Cabinet (https://www.amazon.co.uk/dp/B000PJDUEY) or other cabinets that use the same drawer size. 

Note that the fit is intentionally quite tight. If you prefer something looser, you may want to reduce the thickness by 0.25mm or so.

The original CAD can be found at https://cad.onshape.com/documents/fc67f4ea23e5f8e2749fda20/w/f7c3172b7e365bfd3fd91fec/e/1699240eed98384582218817