Covering the rail with synthetic leather
I started in one corner, planning to staple my way around both ways to the opposite corner. On this pic, you can see my cheap EUR 11 electric stapler bought the day before.
This is the starting corner, which had to be redone later, because the wrinkles were too visible. In total, about 300 staples had to be pulled out and replaced to achieve a satisfactory result.
This corner (the third one) looks much better..
The inside is not as complicated as I feared, as long as you dont cut the insides too far (which I almost did). The material had to be streched on the inside, so naturally, no wrinkles..
As a last step, excessive material was cut away and duct tape was used to hide the staples.