This is how I made mine.
Mine flips open. I keep my scissors, some thread,bobbins and seam ripper in the box so that I can put it away when not in use. I 'hot glue' the round pincushion cover ,that came with the pins I bought, on one cover of the box.
Then I wrapped a piece of sponge with some fabric and 'hot glue' it on the other side of the box cover. Not a cute pincushion but it holds plenty of pins !