Case: 4.2 mm insert holes, M3x8 base screws with the feet

The 4.0 mm holes printed too tight for CNC Kitchen M3x5.7 inserts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

case/README.md

@@ -27,15 +27,16 @@ works if the case stays out of the sun.
 
 ## Hardware
 
-- 12 × M3 heat-set inserts (about 4.6 mm OD, 5.7 mm long; the holes are 4.0 mm
-  and 6 mm deep):
+- 12 × M3 heat-set inserts, CNC Kitchen M3 × 5.7 (about 4.6 mm OD; the holes
+  are 4.2 mm and 6 mm deep, set by `insert_d` if your printer runs tighter or
+  looser):
   - 4 in the bezel's display bosses
   - 2 in the bezel's feet
   - 2 in the body's rear corners
   - 4 on the base's board standoffs
 - 4 × M3×6 to bolt the display to the bezel
 - 4 × M3×6 to hold the D1 board on its standoffs
-- 4 × M3×8 to hold the base on, from below; **M3×10** with the TPU feet
+- 4 × M3×8 to hold the base on, from below (also with the TPU feet)
 
 ## Assembly
 
@@ -48,8 +49,8 @@ works if the case stays out of the sun.
    the anchor on the base.
 6. Put the body on the base and screw it together from below. The base holds
    the bezel in place. With the feet, put a foot on each screw first (the
-   spigot faces the base) and use M3×10. Tighten until the foot is snug; the
-   TPU only needs light compression.
+   spigot faces the base); M3×8 is still long enough. Tighten until the foot
+   is snug; the TPU only needs light compression.
 
 ## Measure before printing