Not one bit of a tool; unless easing a chore counts?

Not revolutionary or grandiose, barely creative, but........
We have two good sized dogs, 60 and 110 pounds,
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with another little 6 pounder,
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drink unbelievable mount of water. Often emptying 1.6 gallon/ 6L bottle in just over a day, one of those inverted gravity fed into a bowl type.
Was frequent task to check sufficient level, such as when we are about to leave for a few hours. Contour of bottle ribs and hexagon shape made it unsure to eyeball from a distance.

So, I dropped a spare fishing bobber [floating] in reservoir; white & bright red easily seen even dimly lit.
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Sometimes the simplest solutions are the most satisfying.

Simple. It's my middle name; occasionally.
Now, when do questions on the weird looking pet come rolling in?

I have to ask, do you have a Possum as a pet, or was that just your sense of humor including it?

I was seeing these last fall, as they would come up at dusk to eat all the black sunflower seeds, the birds threw out of the feeder. I had one that came out after the extreme cold snap in February, as it was smelling the kibbles I left out for the outdoor cat. And it scared the heck out of me when I came out of the shop, and would not stand down. I had to kick it to get it to run off. I suspect it came out of hibernation very hungry. I was seeing raccoons as well last fall, but not seeing them currently in the back yard. We had a big blow here August 10 (the Derecho 120MPH winds, about 100 miles in north south length that ran from central Iowa to Indiana), and I bet every tree that had a hollow in it was taken out. I'm still repairing the buildings. Roofing was blown off, as well as vinyl fascia. I don't think many raccoons survived the winter. But I do see some road kill.

Absolutely do, our 3rd. Sqeeeks, Re-cycle, now Punkin.
Their reputation and disposition entirely different than reality, when hand raised. They develop a very pleasant relation with humans, but sadly do not live very long, four years at most.
Marvelous creatures; nearly immune to rabies Black Widow spiders, poisonous snakes, and eat any insect imaginable. Busy all year long, they slow a bit but not hibernate. The feet, ears and tail susceptible to frostbite. They feed on mice, small birds, the occasional unlucky pigeon, eggs, devour chicken bones [need a lot of calcium], vegetables, carrion too. Ours get yogurt, lap it up like crazy!
One of nature's best scavengers, yet maintain personally very clean. The mouth of 50 teeth opens more degrees than many mammals, have opposed thumbs, as the only marsupial in USA bear up to 20 'joeys' but no more than 13 survive. Part of that, after birth they transit to pouch, in barest state of development, size of a jelly bean - about 10-12mm.
There is a far-reaching troop of possum admirers/ rescuers, spread world-wide. They even appear in cartoons; a few "King of the Hill" episodes, and several "The Simpsons".

The dogs, inquisitive but tolerate her; while she is rather oblivious to them, hence cannot be released.

And to metric_taper directly......sense of humor?
Gaw'd I hope so!

Though not necessarily a tool topic, but some time back we (one of my sons) rescued four of these guys when their mother was found drowned in a nearby creek. Eenie, Meenie, Miney and Moe lived to wander out of their outside enclosure to gradually acclimate to the wild, never to return (we think). They lived inside our home for a time long enough for even me to sense I'd reached the limit of my wife's tolerance. I suppose you could refer to them as "adorably ugly"!!! LOL

Well, to make amends for this stray from the topic, I made an extra large rain gauge from a large vase, calibrated it and put an orange ping pong ball in it so I can approximate rainfall from deluges at a safe distance. It floated too high for my liking and I thought of back-filling it with some clay, epoxy or BBs so it would float at its middle to make reading even easier, but I didn't want to replace the calibration marks I made on my gauge.

Read that to the Ms. "Adorably ugly"; made her laugh but she couldn't disagree more. She's as wild for them as I am for big vertical bandsaws, for example.