Elliot made this nifty hardware button to mute and unmute yourself during Zoom calls. He has full instructions for making on on Instructables:
Press the button to toggle your mute, or hold the button down to leave the meeting (or end it if you are the host).
One great thing about this is that it works even if your Zoom window isn't active… if it's buried under a bunch of spreadsheets and browser windows – no problem – it brings the window to the front and flips your zoom off or on. Quickly un-muting is key to maintaining the impression that you've been paying attention the whole time!
Even better, this all works while you are sharing your screen, so you don't have to do battle with those pesky on-screen controls.
Check the last step for a two-button version that also will toggle your video on and off.