I usually drain the can by keeping the separated top in place and holding it with my thumb I squeeze it against the can while the can is held inverted over the sink. No need for a complicated mechanism.

...minds think alike... (missed out "great" as to say my mind is great, would be like saying hitler is a nice guy!)

...tuna tin topped and inverted ting Sand stated, makes sense really, only problem is if it's oil it leaves greasy remains on your hands.

If you're draining tuna, good chances it's down a drain. Drains mean excesses of water, which usually means a spigot/showerhead/faucet. Use the lid and rinse your fingers off.

Or buy pre-drained tuna in the pouch, probably better either way as even if you did drain normal tuna, it would be easier to trash or store a small pouch for the trash.

Either way, I'd talk to your family doctor about having your balls reattached.

Okay, so lets focus on draining things in-general. I understand that a centrifuge would be useful in a generalist way.

I make spinach bread from scratch. I use a can of spinach and drain the water. Currently I dump the spinach into my hands and squeeze the juices between my fingers. Repeatedly, because spinach holds water well. It probably takes me 5 minutes of dedicated work to get it dry enough so the bread doesn't get spongey near the spinach.

I wonder if a small pan with a strainer in it could be placed in a washing machine and put it on spin cycle. The centrifugal force might sling the juices out while I am doing something else.

The idea being that there are other situations beyond tuna that need to be strained or separated.

As for the straining of the tuna. A marketable idea does not need to be universally desireable. The can could have an attached paper pouch to pour the tuna into that would absorb the oil or water into its fabric, while being waterproof on the outside of the pouch.

A James Rivers Paper Company can easily produce such a product.

You would then pour the dried version of the contents of the pouch onto your plate.

This would also work for other products like sodium for research. Sodium is stored in oil because it reacts with moisture. This would allow for safely transferring the sodium to a user environment.

Tupperware acually makes a little tuna can strainer! My wife got into tupperware and she introduced the neat little gizmo to me and it works awesome. They also had this cool device that cuts and cores apples.