Some thoughts:

Processing small bits of 35mm film. Tape the pieces to a 4x5 piece of glass
or Plexiglas with waterproof tape (the bits the film makers use to attach
film to take-up spools in film loads) or mini-lab splicing tape (I'll bet a
lab would give you a roll end if you asked nice.) Then tray process.

Resolution of enlarged images, you'll need a smaller pinhole for 35mm than
for 4x5 film, you want as small as you can go without getting into
interference range (look it up, I have a sinus headache this morning).

Bigger film, many time I just taped a 4x5 Polaroid back to a pinhole camera
and used type 665/105, then I got both a positive to check composition and a
negative to enlarge. You could also use type 55 in the appropriate adapter
if you have a source for cheap Polaroid (I did at one time).

My favorite pinhole was one I made that mounted a 12 exposure roll of 126
Verichrome pan, now that was fun. Today you could take a cheap 35mm camera
(thrift shop for $1) rip the lens off and use the body as a film transport.

--
darkroommike

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"Dada" wrote in message
...
I am using 35mm films in small boxes, used as pinhole cameras, but I
have some trouble developing them. To do it I use a tank, and putting
every piece inside the spiral require a long time, but that is not the
biggest matter, the biggest one is that, sometimes, could happen that
two pieces of film overlap and the image is lost. Anyone of you that
has some experience with developing film pieces could help me?
Thanks a lot.