Bear in mind that if its CNC routed the tightest internal radius of a cut out will be the size of the cutter, probably 12.7mm, so no sharp corner triangles. If it’s laser cut (what I’d suggest) that’s not a problem.
Solid walnut is not a good idea from a cost / durability perspective. Walnut veneer 6mm ply would be better. Veneered MDF would be even more “dead”, and probably easier to source than veneer ply that thin.
tightest internal radius of a cut out will be the size of the cutter, probably 12.7mm
In wood, you can rout at least 4×D, so in 3mm material you could use a 0.8mm bit to give 0.4mm internal corner radius, which is effectively a sharp corner visually.
Bear in mind that if its CNC routed the tightest internal radius of a cut out will be the size of the cutter, probably 12.7mm, so no sharp corner triangles. If it’s laser cut (what I’d suggest) that’s not a problem.
Solid walnut is not a good idea from a cost / durability perspective. Walnut veneer 6mm ply would be better. Veneered MDF would be even more “dead”, and probably easier to source than veneer ply that thin.