A quick and simple cable clip for 2020 aluminium extrusion. There are others here on the 'verse, but the few I tried didn't fit my extrusion (too loose).

[edit] so I've just printed a few more of these in a different colour and they've come out too tight (cannot be fitted by hand). YMMV but you may need to reduce the scaling slightly if they don't fit. They should just clip into place with minimal pressure and not require a rubber mallet!