Haven’t done it myself, but I’d say the most important thing is to not short anything out. A lot of 1u cases already come with a plastic sheet on the bottom.
Maybe see if you can get some sort of stand you could tape or screw into the case and then the NUC onto that. Maybe NUC board to itx screw holes adapters exist, don’t know.
That’s where I’d start, next thing is getting the ports accessible. Most stuff is available as keystones, at least USB and such. If you can 3D print, an adapter for the io shield to hold some keystones shouldn’t be too hard to make.
Add some case fans as well and that’s about it I’d say.
I remember my first own switch being a Netgear as well. It was a regular 100mbit switch, but it had the words “ProSafe” on it and was made of metal, so that felt really good… Basically it looked exactly like in your picture.
I think that was also the only piece of Netgear equipment I ever really used 😅. Did they ever change the design?