lots! I love add ons. I have dozens of them installed but I disable whatever I’m not currently using. I usually have about 5-10 active at a time. I go for the simple, single use ones ala “unix philosophy” when able because I feel they don’t eat up resources and present less security risk.
They’re so convenient for random little tasks. Like a while ago I had to use this webpage that made you check boxes individually for every single item… like >60 check boxes. I have an addon that lets you bulk select and check boxes. Very rarely needed but great to have.
And I have certain groups of add ons that I use for specific tasks. When I am conducting research I have an addon for zotero, to avoid pay walls, the way back machine, singlefile and other record-keeping tools. Bulk file downloaders; which you need several of because they don’t all work for every situation. Also more advanced history and bookmark interfaces. Don’t need them most of the time.
Firefox is so great about allowing add-ons, it turns it into a powerful tool for all kinds of niche use-cases. I wish it would have a more sophisticated way to manage them. However also I am aware that I’m an unusual user so
I doubt you’ll be able to make something adhere securely long term. if I was to try I would drill holes on the sides only and fill with hot glue. I added hot glue to keys before and it stayed for a fairly long time. Holes on the top will be annoying on the fingertips. There would always be a perceptible difference. And your filler will eventually fall off. if you really wish to pursue the project you will need to investigate the material your keys are made of and what will adhere to it.
You’re basiclaly trying to DIY double shot keys. I think it would be really hard to duplicate this without a factory:
I suggest you go on ali express and buy shine-through key of the same profile and compatible texture. You can buy blank keys or modifier keys in small amounts, even one at a time depending. Make sure to get the correct size per your layout.