Add 3D-printable desk case for the VFD and a WEMOS D1 R1

Parametric OpenSCAD design: 15 degree bezel holding the display on M3
heat-set inserts, slides into the body; base carries the board with the
DC jack and USB reachable through the back. Includes STLs, previews and
collision checks.

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

case/README.md

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+# Desk case
+
+A 3D-printable desk case for the Samsung 20L203 VFD and a WEMOS D1 R1
+(UNO-sized ESP8266 board). The display is tilted back 15° and bolted to the
+front with M3 screws. The DC jack and the USB port are reachable through the
+back wall.
+
+<p>
+  <img src="preview.png" alt="Case preview" width="49%">
+  <img src="section.png" alt="Cross-section: display on the bezel, board on the base" width="49%">
+</p>
+
+Outer size: about 208 × 112 × 86 mm (W × D × H). The parts need a print bed of
+at least 210 × 115 mm.
+
+## Parts
+
+| File | Print orientation | Notes |
+|------|-------------------|-------|
+| [stl/body.stl](stl/body.stl) | upside down, top on the bed (as exported) | Sides, top and back wall. No supports needed. |
+| [stl/bezel.stl](stl/bezel.stl) | face down (as exported) | Front panel with the window and the display bosses. |
+| [stl/base.stl](stl/base.stl) | flat (as exported) | Floor with the board standoffs and the screw holes. |
+
+PETG is a good choice: the display warms the inside by a few degrees. PLA
+works if the case stays out of the sun.
+
+## Hardware
+
+- 10 × M3 heat-set inserts (about 4.6 mm OD, 5.7 mm long; the holes are 4.0 mm
+  and 6 mm deep):
+  - 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 × M3×8 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
+
+## Assembly
+
+1. Melt the inserts in.
+2. Bolt the display to the bezel from behind, glass facing the window.
+3. Screw the D1 board onto the base, with the DC jack and USB edge at the back.
+4. Slide the bezel, with the display on it, into the body from below. Its edges
+   run in the grooves in the side walls until it stops against the top.
+5. Connect the display cable. The MAX3232 sits inline in the cable; tie it to
+   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.
+
+## Measure before printing
+
+The dimensions come from the 20L203**DA12** datasheet. Your board is a DA5, so
+check these against yours and change the values at the top of
+[vfd-case.scad](vfd-case.scad) if needed:
+
+- `disp_hole_inset`, `disp_w`, `disp_h`: the display's mounting holes, 182 ×
+  56 mm apart.
+- `glass_x0`, `glass_y0`, `glass_w`, `glass_h`, `glass_depth`: the glass
+  position and the distance from its front face to the PCB.
+- `usb_pos`: where the micro-USB port is along the D1's back edge (38 mm from
+  the jack side is a guess based on the UNO layout). Also check `jack_pos`.
+
+If only the display is off, it's enough to reprint the bezel.
+
+## Changing the design
+
+Open [vfd-case.scad](vfd-case.scad) in OpenSCAD. Every dimension is a variable
+at the top, including the tilt, wall thickness and clearances. Export a part
+with:
+
+```
+openscad -D 'part="body"'  --export-format binstl -o stl/body.stl  vfd-case.scad
+openscad -D 'part="bezel"' --export-format binstl -o stl/bezel.stl vfd-case.scad
+openscad -D 'part="base"'  --export-format binstl -o stl/base.stl  vfd-case.scad
+```
+
+`part="assembly"` shows everything with dummy display and board models, and
+`part="section"` shows a cut-away. The `check_*` parts are collision checks;
+each one must render as an empty object:
+
+- `check_body_bezel`, `check_body_display`, `check_bezel_display`
+- `check_body_base`, `check_bezel_base`, `check_display_base`
+- `check_board`
+- `check_insertion`: sweeps the bezel and display along their slide-in path
+  through the body.
+
+Faces that only touch can show up as a zero-volume result, which is fine.