Replacement Holder for paper kitchentowels 

Intended to hold a spool with diameter when full of 130mm.

Slots are for mounting to a wall and are 30mm in length to acommodate for varying hole spacings between (in my case existing) drillholes with wall plugs

The center axle for the spool with towels to reside in is not part of the model and is supposed to be bought as round stock. 

That axle would then have to be slit into holder brackets that then slide into the slot in the actual arm part of the holder (the last image [CAD] illustrates the concept)

The displayed holder brackets are intended for 35mm (nominal) wooden round stock the spacing between the holders is dependent on the length of the spool. 

The holder brackets are not part of the design as the availability of wooden round stock may vary across the globe with respect to the selectable sizes but two stacked cylinders with a sufficently sized hole for the round stock to go into on one side should be easy enough for anyone.

the design is possibly way over built for the loads it will face in practice!