Saw an advert to buy such a thing and thought, I can make one....

The advert showed things like - extension lead plug board fixed to skirting, remote control, etc

So here you go.

Stick or screw one piece to a wall or cupboard or door, fix the other to the item to attach and slide it into place.

Can be used horizontally or vertically, note the stop at one end for vertical use.

The STL (and STEP file) contain two objects. They need to be separate to print.

Eg with PrusaSlicer : right click the object and select 'Split'. Then move the two objects and rotate and lay them side by side.