From the looks of the case, it doesn't really need to be made supple, contrary say to a neck strap. What i believe is needed is a conditioner. Something you'd use on the leather seats of your BMW (Beemermark ;-) ).... something that doesn't leave an oily or greasy residue. We used to use 'dubbin' and similar products on our rough out climbing boots. The best conditioner i've used are the products offered by Lexol. I used it on my leather view camera bellows..... & you could use it on leather furniture. What would you use your homemade 'dubbin' for...? I sure wouldn't let it anywhere near a view camera bellows.