Penny project

I would use transparent E6000 and then coat with a non-yellowing spray varnish when the project is dry.

I used E6000 to glue pennies on a table top about 20 years ago. I still love the table, and it sits in my office. I suppose you could use a poly clear coat, but I've never used anything on mine and it still looks like it did on day one.

e6000

I would use either hot glue or a tube of 6000, then epoxy or polyurethane to cover them up.

Use E6000 glue to glue them down, and then pour poly over the top after they have dried to seal them and protect them...and leave a shiny, smooth finish.

Barbara, if you have enough pennies you might consider Super Glaze as shown in project "Broken DVD Countertop, a Labor of Love" https://www.hometalk.com/diy/kitchen-dining/kitchen-dining-furniture/broken-dvd-countertop-a-labor-of-love-32146492?se=fol_new-20171008-1&slg=e9b9423adb24fe6cc9e7ec423576c7f0-20830881&post_position=7. They would never be usable again but they would retain their shiny brilliance and could always be seen.