I printed with 3 walls, 4 tops, 3 bottoms, 15% cross-hatch infill, 0.2 layer height (for better layer adhesion) in Sunlu PLA+.
Model has slight chamfers to insert a board (600x210x16mm).
In case anyone wants to update the legs to their size, here's an onshape link to the design:
https://cad.onshape.com/documents/bf67278e03349017cb606c60/w/fa8d3208548e4b29a0c0fe79/e/4257b2d2bfc65a4760dfdf25?renderMode=0&uiState=666028096259df03ebbca07b
The author marked this model as their own original creation.