Backstory
I wanted to have some things easily grabbably reachable while in bed, e.g. bluetooth keyboard for watching movies from bed. So I decided to attach a Skadis to the side of my nightstand.
Model
This mount attaches into the right angle at the outer edge of furniture, like a tabletop or a nightstand. You'll probably want to print >1 of those - I'm currently using 2, one per edge of the Skadis.
Unlike obri's model, this attaches to the very edge of the furniture, and takes up much less space on the top side.
Unlike IKEA's official Skadis connectors, this does works for furniture that isn't a desk top. IKEA's thing assumes that you can clamp and squeeze the mounting surface from both sides which doesn't work for weirdly shaped tabletops or nightstands.
Prerequisites
You'll need to drill holes in your furniture.
You'll need, per each copy of this model:
Regarding “right length”:
For the 2 wood screws that will go in from the top, you want a length of ~8 mm + however deep you want it to drill into the top of the furniture:

For my usecase, I used 35 mm.
For the 1 wood screw that'll go in from the back, use 20 mm + desired bite depth:

I believe I also used 35 mm here.
Installation
Caveats
I'm not a mechanical engineer and have zero idea how much load this can take. It's working OK-ish for me with a light load on the Skadis.
The author remixed this model.
I originally tried using this model for my needs, but ended up FreeCAD-ing up my own, to use up less table space and have less horizontal clearance. The model I have now isn't very related to this one anymore, but it deserves big credit as inspiration.