Sanding and Removing the Arris — How To Make A Chisel Tray

Use 240 grit sandpaper to even out any irregularities on the surfaces. Remove the arris (sharp, 90° ridges) to the top rim using a smoothing plane. This not only strengthens them, but it also gives the box a much nicer feel and avoids the sharp edges breaking off over time.

Note: Do not take the arris from the bottom rim as that is unnecessary and would only create the appearance of a gap against the base when glued up.

Make the corners of the joints a little less sharp

When taking the arris, make sure your plane is skewed towards the outside