Just a few quick hints if you want to build one:
buy the Etekcity EL11 scale. I haven't tested it with other scales
- use a pair of pliers to unscrew the (glued in) luggage-hook (counter-clockwise :) )
- open the scale (2 screws in the back)
- unscrew the PCB (3 screws)
- unscrew the load cell (2 screws)
- unsolder the load cells 4 cables
- solder 4 wires as long as you need them (don't go too wild, maybe 50cm max or so) to the board. note colors and position!
- push wires through the opening in the case where the hook was
- put PCB back
- close case and tighten fasteners
- add heat shring tube to the wires
- solder your extension wires (in the correct oder of course!) to the load cell wires.
- shrink heat shrink
- cut M3 threads into the load cell case
- put load cell into the case (secure each corner with a dab of glue)
- put on lid, fasten with M3 screws
The hole in the lid is 8.2mm to account for shrinkage after printing. 8mm steel rods or tubes fit well.
I added the STL, STP and FreeCAD files in the files section. Happy hacking!
- the PCB has programming/debugging pads easily accessible, haven't bothered looking if the scale maybe puts out a serial stream like many calipers do
- the scale has a thermometer included
- you can add another hole in the bottom of the case to add the luggage-hook back. That way you can still use it for measuring hanging weights. (this will bu quite uncomfortable because of the small case though)