3/4 plywood for shelf
30mm foam for insert
1/4 mdf for insert base
1/4 - 1/8 stock bits
Track saw for long cut (optional)
3M 77 spray glue
Cut the shelf first.
Cut 1 tool base in MDF on the shelf itself, or a even larger one. Glue the foam to the MDF while still fixed to the shelf.
Lower the shelf, cut the foam: no need to re-grid, lowering the shell maintain lateral measurement.
Repeat for the next insert.
Use bit_1 and bit_2 to cut the insert for the tape rolls.