Removable Cross-bar for 25x25mm timber sections

Applications
I designed this for a storage solution where the user can choose the quantity of bar elements, and their position. 

Timber
It is for 25 x 25 mm planed timber. This is the finished planed size you need (some hardware stores are old-fashioned and sell planed timber according to the pre-planed size!).

Preparing the bar ends
Nominally the removable bar (crossbar) ends 18 mm from the side-member (rail) timber.
The end(s) need to be notched according to the image, to accept the printed endpiece. 
An oscillating power tool is ideal for this. Hand-saws are also possible but will take longer. 
You also need to chisel out a space for the latch mechanism.
Don't force-fit or hammer the endpiece: if it's too tight, see where you need to remove more wood.

Fitting the latch
The optional latch prevents the fitted bar from being knocked away accidentally. You might not require it for your application.
The latch is a little tricky to assemble. Don't rush this but ease it into place using as little force as possible. A small screwdriver can help, and also pliers (see images). Be careful of the tiny spring, and push this under its threshold when the time comes.

Toothed side-rails
The rail pieces are 110 mm long each, with tooth pitch of 5 mm and screw holes at 55 mm pitch.

Retaining screws
Use Ø3.5 mm woodscrews. Length 20 mm min. recommended.

Safety
Please be aware the device has limited strength and should not be used where failure might cause injury.

FreeCAD source model :  See reference application  
https://www.printables.com/model/601126