Aligning leather seam edges without using pins
If you've ever tried sewing with leather, you'll find tat almost none of the conventional dressmaking techniques you've learned so far can be used quite the same. Lather requires special handling, treatment and can be considered its own form of "art" and craftsmanship.
If you are sewing a leather garment, you'll soon realize that leather cannot be pinned as you would conventional fabrics. Not only is pinning very difficult to do, the pins leave permanent perforation marks on the leather surface.
You should double check your seam alignment before applying the final machine stitch because if you made a mistake and have to redo the seam, the stitch preformation marks will be left on the leather surface and be challenging to hide.
Perhaps one of the easiest ways to keep leather seam edges aligned in the machine stitching process is to use paper clips. Not only are paper clips readily available and most likely something you already own, they provide a very stable aligned and are easy t remove as you apply the stitch. The leave no marks behind and are extremely easy to clip on to matching leather edges.
Another option for keeping leather edges aligned without using pins is regular double sided tape or quilting tape. You should first test that the adhesive does not damage or leave permanent mark on the leather surface, especially if working with regular double sided tape which has a stronger bonding effect. Quilting tape works the same as a regular double sided tape but is safer and gentler. You can purchase quitting tape at any of your local fabric or craft stores.