Some photo's of tools and methods used.
Probably not the correct way to do it, and certainly not the only way, but it worked for me.
A tidy work space is essential...
The leather used was 2.5mm thick 'Veg tan' bought from eBay, £15 for about 12"x12" square. Nice stuff to work with and cuts easily with a sharp scalpel, using a straight edge or freehand for the curves. I have since bought a huge piece, almost a whole skin, again from ebay for £15. Waiting for it to arrive, it's a bit thicker at 3.5mm. Thinking of having a go at some reel boxes next.
The pattern was marked out on thin card (Corn flake box) and tried for fit around the tube (more on this later). The pattern was then transferred onto the leather by tracing around the pattern using the point of a blunt knife. This leaves a clear line on the leather which is easy to follow with a scalpel.
Having cut out the leather, I found it was too small when wrapped around the tube...I hadn't allowed for the thickness of the leather. Another one was marked out, 1/4" longer, this fitted fine.
Having watched how to do the stitching on 'You tube' I marked a line about 3/16" in from the edge of the leather using a pair of dividers.
The holes for the stitching were made using a 'Pricking iron', a set of four irons from eBay cost £7.00 inc postage. Brilliant tool, just line it up on the scribed line and hit it with a hammer, the result is perfectly spaced holes.
For the stitching I used 18/4 waxed linen thread, again from eBay, £6.00 for 50 yds inc 2 saddlers needles.
There are dozens of video's on 'You tube' showing how the stitching is done, I used 'Saddle stitch' which uses one length of thread and two needles. It's really easy, but does make your fingers sore.
To make the 'Lid' for the top of the leather cap, I used the offcut from the aluminium rod tube and a large socket, squeezed up in the vice. Worked a treat.
The resulting lid was glued into the top of the leather cap using 'Copydex'. Then the holes for the stitching were made by drilling through the already punched hole in the outside of the leather cap with a small drill bit in a battery drill.
The part of the job I found most difficult and time consuming, was making the brass clips from 1/8" brass rod. I had to anneal the brass frequently before bending or flattening out the ends. I had repeated failures before making a bending jig from a scrap of mild steel angle. It was then a bit easier, but still a pain. The clips were cleaned up using needle files and wire wool and fixed to the rod tube using 2.5mm stainless steel machine screws. I would have used brass screws, but couldn't find my BA taps...
After cutting the aluminium tube to length, the end cap was turned from scrap brass bar and epoxied in place.
I have rambled on long enough now.
I hope the above is of some help.