The collage for this paperweight was made with reproduction milk caps.  You can use vintage pieces if you wish.  Just check to make sure they're not rare and valuable before you start cutting and applying glue.  (You'd be surprised how much an old milk cap can be worth for its artwork or the particular town it's from.)

The milk caps were produced by Tim Holz (Item #TH93684) and are packaged in a set of 50 pieces.  Most pieces are the larger size, with a few small and medium ones scattered in the mix.  (These were featured in my earlier post: Finding Craft Store Bargains for Your Paperweight Designs.)

I applied some scrapbook paper to the adhesive side of the paperweight kit's mounting board.  The first layer of milk caps was secured to the paper with white glue. You can trim the milk caps to fit the board before you glue them down, or wait for the glue to dry and trim everything that extends beyond the edge of the mounting board.

As you're building your layers, it's important to check your work to make sure everything will comfortably fit within your paperweight.  I used hot melt glue for the second and third layers because the first layer wasn't level.  I placed my favorite milk cap designs on the top.