If you would like smaller amounts, why not try a locket? Like those heart lockets you store photos in and wear on your neck?
I bought this one on etsy.com. Because I knew I was going to pull it apart, I thought it be best if I bought a cheap one. So I searched up "pocket watch" and selected the "lowest price" option.
When picking them, make sure you know the size. Some of the really cheaper ones are tiny little sizes, unless you want that size!
I waited 2 week for mine to arrive from China.
Perfect size! 40mm radius. And I paid $7 USD.
1) Press the button at the top (remember this part of the watch, it is important!! THE BUTTON!). The button opens up the front cover.
2) Here I took what ever tool was nearby and smashed the hell out of the watch face. This is why you wanted a cheap one because the watch will be of no use here! Anyway, the plastic cover should break up and you can take it off.
3) After, I turned the watch around and used a flat head screw driver to pry it open. Mine had a small groove where you can place the screw driver and lift it open.
When that was done, I just pulled everything out; smashed up all the insides and snapped the rod that was used to change the time. Normally I'd give it to a toddler, they destroy things in seconds... but I wouldn't want it choking on anything!
4) Remember this button? Well its a THICKER rod than the 'time changer' one - or whatever you call it.
Here I super glued down that round thing around it. So just glue down that bit without getting any glue on the rod. You still need it to be able to press down to release the front cover.
Hopefully you have everything correct here. If not, I'm really sorry! My instructions are horrible!
Now clip back in the back cover and there you have an empty pocket watch case!
If you glued it correctly, when you push the button down the cover should pop right open like normal!
This would also be a nice way to store homemade lip balm. Maybe if you're careful enough you can glue in a small fitting mirror onto the inside of the front cover.