It sounds like you're looking for a "key legend", which is sheet with all of the letters printed on it that you can cut out and replace under the glass key caps on your typewriter.

Richard Polt has a PDF on his web site that you can print. I'm not sure which machine it is for (My Underwood 5 is in storage): https://site.xavier.edu/polt/typewriters/keylegends.pdf

A couple people sell them on ebay: https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=underwood+key+legend&_sacat=0

Robert G has a very helpful article on the process he's used to restore key caps: https://badonoer.blogspot.com/2022/03/brightening-of-glass-typewriter-keys-of.html



 

I've noticing some Goodwill stores (e.g. Seattle) moving from shopgoodwill.com to ebay. So, maybe each store is moving to find the site that most suits them. I've wondered if Fedex gives shopgoodwill.com a good deal, which may be good depending on where the Goodwill store is, and that this may be a factor. The Seattle store is very near USPS, UPS, and Fedex hubs, so they have more options.

Here's another for auction (not affiliated with the sale): https://www.liveauctioneers.com/item/190600795_vintage-hermes-3000-s-typewriter-wcase. 

Opening bid is $350. (It was on the block last week with an opening bid of $400, but nobody bid). 

Looks to be in VG shape, though. 

After watching a Joe Van Cleave video, I've started using newsprint for ephemeral subjects. It's really inexpensive, works well (I use the Avery backing sheets Pete E recommends), and takes ink nicely.

George: I've never heard of Bungubox. Now I've got another fountain pen ink rabbit hole to go tumbling down. (The last was Wearingeul). Thanks! Good thing I just built a bigger ink sample case...

Is the "hammer" the metal sheet that separates the next staple from the rest and drives it into the paper?