If you are stuck on doing it yourself, I would get a TC 2824 from Thomas along with his KH dial and hands. Keep your Swiss 2824 in a drawer for now.
Because I prefer lugholes, I'd get a sterile 3135 sub case from Startime. I believe the bezel is included, which is excellent.
Gen 25-295 crystal, gasket, insert.
If all goes well you have a great sub. Expand the lugholes to 1.25mm so you can use gen 2mm spring bars.
Once complete, then you can contemplate using your eta 2824 and using the H4 pinion from the TC movement along with the included movement ring.
Whatever you decide, good luck and have fun. Failure is the only way you learn.