When it comes to cheaply using 16mm film I think the two hard parts are developing and telecine. Hand processing is difficult without a decent daylight tank. Here are some of the tanks that I have used in the past and what I currently use.
I am lucky to have inherited a good bit of old photography stuff. Both of these tanks were used by my grandfather many years ago. The square tank is a 4×5 cut film tank that will work for processing super 8 or you can stuff maybe 1/3rd of a roll of 16mm in there, but it won’t turn out very well.
Once I really started working with 16mm I really needed a bigger tank and I pick up one of these on ebay. It’s a Jobo 2800 system tank that is made for paper developing. It worked alright until the top lip on the tank started to deform. I replace the drum, but I still don’t like how delicate the tank is, so I started to think about making my own.
So I headed off to the lumber yard and started to stalk the plumbing section. I bought a piece of 6″ pvc pipe and various fittings.
The tank turns out to be light tight and pours just about as fast as the Jobo tank. The top seemed just a little too complicated. So I kept going.
This is where I would recommend people start if they want to make an easy and inexpensive tank. The top is much easier than my previous version and work almost as well. The only issue I have had is that sometimes an end of the film wants to pour out with the liquids. A quick inversion while pouring will remedy the situation. It is made from 1 foot of 6″ pvc with two caps and 4 – 1″ schedule 40 street elbows. I drilled a single hole in the top cap to fit the outer diameter of the elbow and glued it all together.
The 6″pvc tank body does need to be sanded down a bit so the lid does not stick on too tight. Also you might noticed that I didn’t bother to paint the body, I found the plastic thick enough to block light (ymmv). The 6″ pipe sections are about 10″ to a 12″ long making the tank just the right size for a 100′ roll of film with a little wiggle room. I have used the tanks many times and they have proven quite easy to use, cheap and durable.
16mm Adventures 
What do you use for a reel to hold the film?
Nothing, you just stuff the film in. You never know what you get. This is not the type of processing you do if you want precision. Although after doing 30 rolls or so I end up with very few bad spots on the finished product.
I’m an experienced Super-8 spaghetti processor about to try 16mm. Love the zigzag tank! Is that light tight enough for fast film? How much developer do you use for one 100ft spool? Would 2.5 litres be enough?