I'm a prosthetist and we use a glue called DUALL by R-H Products Co, Inc, Acton, MA, 01720. Any good shoe repair store should this or something similar. Apply 2 coats to each surface to be adhered; allow each one to dry completely. Then press together carefully. If you get a wrinkle here you may not get them apart w/o using acetone. WE use them for bonding leather to a range of items. It works very well and last very long.