So, here's the start of a box as stated above.
The dimensions of the box are
a) Internal: 220mm x 320mm
b) External: 252mm x 352 mm.
The box is designed to accommodate A4 paper, or to be set up as a Jewelry or desk box.
The sides are Spalted Brazilian Walnut (AKA Ipe) and the base is Tasmanian Blackwood.
The sides were thicknessed to 16 mm then mitred using a Kapex SCMS.
Trenches for the base were cut using a Domino with a 5 mm cutter. Cuts were performed by using the maximum cut width and overlapping each plunge to avoid a "wavelike" base to the trench.
The Blackwood base was made from off cuts glued together and thicknessed to 4.98 mm.
The internal surfaces of the box and the base were sanded using an ETS150/3 using 80,100,120,150,180,240 and 400 grit, then oiled to saturation with Wattyl Scandinavian oil and then wet sanded using 400 (the same disk as used previously), 500, 800, 1200, 1500, 2000 and 4000 grit, then wiped with a clean cotton cloth.
The box was then assembled. During glue up, band straps were used to hold the pieces in place. Squareness was checked using diagonal to diagonal.
After glue up, the external surfaces of the box were sanded and oiled as stated above.
Fig #1 shows two of the panels, one sanded to 400g and the other after oiling and wet sanding.
Fig #2 shows the assembled body of the box with the Blackwood base visible.