Sort of accidentally started a new build...

[Rabbit]

That is the challenge, and I don't think I have anything sufficiently precise to cut down the sleeves. I could use a hacksaw but the nut shape makes them really difficult to try and hold securely in a vice.
I have a Dremel-alike thing but it is spectacularly useless at cutting any kind of metal. It's great at destroying cutting discs though.

That may have less to do with the tool and more to do with the discs you are using......

[McCreed]

That may have less to do with the tool and more to do with the discs you are using......

I'll second that.

As for holding the threaded sleeve, I made small clamping blocks out of pine to hold the sleeve in just a hobby vice.
Clamp the two blocks together, then drill a hole just smaller than the sleeve diameter centred right on the where the two blocks meet (like two halves of a mould).

This will hold the sleeve in a secure horizontal position without risk of squashing it out of round. You can make indentations in the blocks where the "nut" portion will sit, but I found the pine was soft enough to indent from the clamping pressure and not compress the nut.

I'm sure there is a proper name for this kind of "device" but I don't know what it is...

[blinddrew]

That may have less to do with the tool and more to do with the discs you are using......

Any recommendations greatly received (if not for this project then for a future one).

[McCreed]

Any recommendations greatly received (if not for this project then for a future one).

DREMEL Reinforced Cutting Wheel

If you're using the brownish red wheels, they're mostly rubbish for metal. They'll work but wear down very quickly (as well as explode).
The ones linked are fibreglass reinforced.

It's also worth (IMO) investing in the EZ-Lock Mandrel and using the EZ-Lock wheels as well.

EZ-Lock