I wanted to make a foot bath bomb for Mother's Day, but couldn't locate any powdered citric acid here locally :(
I did find out Alka Seltzer is mainly baking soda and citric acid so I decided to Google it and did a version of what I found.
I got a box of 36 effervescent tablets for a couple of bucks - lots cheaper than the real thing! - so that'll make 18 foot fizzies, unless you don't mind the stamp on the top, then you can skip step 4 and have 36, but mine were made as gifts so I decided to cover that stamp up.
lay out the effervesent tablets on a paper towel face up (if they have anything stamped on them) but mind the weather - if it's too humid out when you're doing this they'll start to bubble from the moisture in the air before you can get to them all. you might need to only open one packet at a time.
place a single drop of peppermint extract (tried the oil - never would dry for me) on each tablet and let them start to fizz.
once they're kinda sticky and bubbly, take two and mash them fizzy sides together being careful not to break them.
if they're too fizzy wait a little longer, or just wipe them off with a paper towel and try again.
place back on the paper towel to set up.
if they continue to fizz up and slide off center while sitting, wipe off and press together again.
when they start to dry they'll calm down and stick tight.
mine took a few hours to get good and stuck, but once there doesn't seem to be any moisture left, put them in an air-tight container.
I put mine in a pimento jar 'cause it's cute and little :P
when you're ready to soak your feet (or even your hands) drop a couple of tablets into your warm water basin (my husband prefers them under his feet) and enjoy :)
they make the water soft, and while they're fizzing they release peppermint scent into the air.