So, I've ended up with a hoarde of 135 (35mm) film cans and I was wondering what they could be used for after they are no-longer needed for holding 135 film.

Answer: Film cans for 120/220 film! (To keep them in the dark after being exposed.)

Yes, I know there are commercially available cans, but I bought the last 6 that Houston Camera Exchange had, and haven't been able to find more. Besides, it's a nifty way to recycle the cans without all those noxious chemicals... :-)

This works best with Kodak cans. A quick trial shows that they are slightly tapered and the bottom end of one can will fit tightly into the top of another.

Materials:

    2 Kodak 135 film cans, preferably black, with one available lid.
    Adhesive/sealant that dries flexible (optional).
    Electrical tape.

Equipment:

    Knife or other implement capable of cutting film can material.
    Empty 120/220 spool (used as depth gauge).

Procedure:

    Remove lids from cans and set aside.
    Cut the bottom out of one can (suggest running a hobby/modeler's
    knife along the corner between the bottom and wall from the inside).

    If desired, apply appropriate adhesive according to directions.

    Carefully insert the bottom-less end of the one can into the open
    top of the other can.  Be sure not to let the bottomless can buckle
    during assembly.

    Using the empty 120/220 spool as a gauge, continue to press cans
    together until lip of open end is about 1/4-inch from the spool
    flange.

    Secure the joint between the two cans by wrapping with electrical
    tape.

    If adhesive was used, be sure to allow plenty of time for curing
    and evacuation of solvent vapors which may harm film.

    Replace cap on open end of film can.

The resulting can should be able to accomodate a 220 roll of film even if still in its individual foil/metalized plastic wrapper.