Where can I find small wood screws to mount a lens ring? A #4 screw has too large a diameter.

Steve

some times ACE hardwere #2 by 1/4"

A good hardware store, not Home Depot or Lowe's, should have #2 wood screws in 1/4 to 3/8 length.
An alternative is to use #2-56 machine screws and nuts or 3mm machine screws and nuts. Paint the nuts flat black once the flange has been mounted. Brass are most commonly used in lens mounting but zinc coated will work.

Those little parts drawers at your nearby locally-owned hdw. store should have the little machine screws, like the 2-56 size. Alternatively, try your local model railroad hobby shop. Mine has sizes down to 00-90---too small for my pudgy fingers (of course, the rest of me isn't pudgy---wink, wink).

I can suggest two sources-your local model train shop, and in San Diego, a store called Marshall's Hardware. Train stores carry 1-72 & 2-56 slot & hex head machine screws (brass), and sheet metal screws in the same size. At Marshall's they carry the slot, as well as wood and sheet metal down to #2, maybe even #1. Marshall's number is (858) 271-5555. Nice thing about Marshall's-priced individually and by the box, so you buy just what you need.
James