When I bought a set of 6 Ikea SKÅDIS boards and was putting them up on the wall I wanted something to allign them perfectly.  

So I took my calipers, took some measurements and opend fusion 360.

First I made the “mini”s so the boards could be connected and aligned. Then when I installed them I missed the support of the wall so I quicly made the “riser”s to fil the (17mm) gap.

But not wanted to print out two pieces and sticking them together I made the “full” models.

Printed them out and put them on the back.

Result of “Skadis connect 4 boards full”.

Result of “Skadis connect 2 boards right-left side full”

Result of “Skadis connect 2 boards up-down side full”

Result of “Skadis connect 1 board corner bottom-right + top-left full” (you need 2 of these and 2 of “Skadis connect 1 board corner bottom-left + top-right full”.

End result:

The additional benefit is you lose the lower screw holes so it looks (IMHO) visualy better (and when adding “IKEA Skadis Screw Cap” by @ledsi_351866 it's even better.

I uploaded all models in case people want them but standard you only need the “full” files. 

I used the original metal back plate/rail to secure them to the wall but if you got a flat surface on your wall you can probably use good double sided (nano) tape to secure the board connects to the wall (and also use it to connect connects to the boards). Havent tested this myself tho!

And for all things you havent made yourself (including these), use at your own risk!