I got the leather pieces from ebay. If you search for leather at hobbies and crafts section, you'll find plenty of them at very good prices. Try to get a thinner (1-2mm) leather since it is easier to work on.
For this instructable you need:
- a saddle in bad shape
- scrap leather large enough to cover it
- impact adhesives (i.e., Evo-Stick for UK)
- a ballpoint pen
Below are the origins of the saddle and the final looks of it.
There are not many hazards/risks with this job. Watch out what you are cutting with scissors, I know one story involving scissors where a joke ended up with death. Impact adhesives are mostly solvent based, so I advise you to do this job at a well ventilated area, or you may get high (unfortunately :-). But really, don't forget that these adhesives are carcinogenic, really.