I used to collect these Gettysburg relic desk sets about 1980-1990, and as I often visited the battlefield then
I was often able to find these at local shops. They were expensive then, but since have become much more so.
I sold off all mine long ago, and the only one I have today is one of a block of wood with an ink well embedded into
the top, and it says "Jennie Wade" on it. There is an ancient fired Civil War bullet seen embedded in the front.
I placed a photo of mine up on this site, some time ago, and I expect it is still here.
I expect that the bullet is from the battle, but it was put together otherwise long ago. I would estimate 1890-1900.
Some of these have several dropped bullets, and maybe a portion of a shell, or bayonet, and even relic buttons on them.
Yours with "Little Round Top" is a very nice one, and a bit unusual. Also a very old one.