A tool is a thing for helping you put things together, take things apart, and measure things. Adhesives, lubricants, penetrating oil, tape, solvents…these are all tools, just as useful and important as a screwdriver or a hammer.
One of my favorite tools of this type is Sugru. Sugru is a putty that you can work like clay, sticks to almost anything, and hardens to a firm silicone rubber; about as firm as a sex toy. It’s food safe once it’s cured, heat resistant, solvent resistant, dishwasher safe… It’s amazingly useful cool stuff.
It’s available in 5 colors and comes in a little foil pouch. Once you open it, you have a few hours to work with it, and then it’s started to stiffen up. By 24 hours it’s pretty much set all the way through. You mold it into the shape you need and let it set and there you are. People use it to replace or make better the grips of their tools. (instead of a tool that is designed to fit anyone’s hand pretty well, wouldn’t it be better to have a tool that fits your hand perfectly?) People use it to make little one-off brackets and hangers and hooks. People use it to repair the strain relief on their gadget cords, right at the plugs where they always seem to fray. I’ve used it to build a little curb around the on/off switch of one of my tools that was always getting turned on in my bag. I’ve used it to make a little bumper on one of my glass shower doors so it doesn’t slam quite so alarmingly into the other glass shower door. I have some in my camping gear for emergency repairs.
You do need to make sure the surface you’re sticking to is surgically clean for best results. Any finger oil, dirt, dust…the sugru is going to stick to that instead of the thing you’re trying to stick to. For some things that will be fine; the sugru will still stick well enough. I didn’t super-clean the tool I mentioned before I built the switch protector. But I did super-clean the glass before I built the shower door bumper; it does stick to glass, but not as well as some other things (the ultra-smooth surface is hard for it to get a grip on), and I know it’s going to get a lot of whacks.