David Antscherl, in The Fully Framed Model, Volume 11, discusses this issue and concludes that either a grating or clerestory-style companionway would be appropriate for a 1779 vessel of 300 tons. On my Pegasus model I opted for the more visually interesting clerestory-style companion.
I made my own and they were fun to make. I suppose you could make them without a lathe but it would be a lot more work. But, if using a lathe, the order of operations is critical. As well you'll need a mill with a rotary table or drill press with a holding jig for the deadeye holes. Or, you could use CNC if you have the equipment https://modelshipworld.com/topic/19253-le-gros-ventre-by-marsalv-148-pof/page/15/#comments.
If you have none of the above and need only a few then I would buy them from Syren as theirs are the best commercially available and pennies apiece. Otherwise the investment in equipment would be hundreds of dollars!
dvm27's post in Skylight Measurement for HMS Pegasus 1776. was marked as the answer