I switched to trough development for my 120, to ensure even skies,
especially in
bright scenes, which included snow, but were also given considerable
exposure for shadow detail. I had been getting extra density on my
edges with reel development.

I build the troughs out of vinyl rain gutter. The end caps were placed
on 36 in.
troughs, allowing for 120 film and some space for hands on each end.
The trough
is just the right size not to use much more solution than a tank. I
fill it with 2000ml, but you don't actually need that much, 1200ml
would probably do.

Two rolls are developed at one time by holding them together base to
base with a clip, which also prevents curling. The film goes into the
developer evenly and
avoids any added development at any point on the film, which could
occur with the see-saw method. Agitation consisted of gentle moving of
solution, separating the base with a hand movement, and flipping the
top to the bottom.
I flipped the top to the bottom by twisting one end then slowly
continuing the twist the length of the film by hand.

After stop and fix. I turn the stop trough into a washer by laying a
hose from the faucet into and along the entire length of the trough,
with punctures along the length to ensure even washing. A plug at one
end is removed, and the waste water flows to the sink. The hole should
be small so as not to drain too fast.
If you use an acid stop instead of plain water, just make an extra
trough for the washer, so you don't have to recant the chemistry.

The only problem I've encountered so far is returning any solution to
a container. A large mouthed funnel would help control the excessive
splash at the gutter end cap. But thats about it. Pretty smooth
operation, the space taken up is minor, and cost was $22.00

Ken Smith