I found a tweed jacket for £8 at the local hospice charity shop which had a weave I thought was not too garish. I don't think it could have been worn much as some of the pockets were still tacked up. It certainly looked new to me.
The first thing was to remove some of the length as normal jackets don't always look right with a kilt. I wanted enough depth of excess material to fashion a sporran 'skin' of the same material, so I had to calculate this. I had a sporran which was beginning to show signs of wear, and was ideal for this.
Following the design of the weave I cut away the calculated amount of tweed, and a similar amount was removed from the lining.
The pocket material depths had to be shortened accordingly and sewn across the bottom of each pocket again, though they are so shallow now that they aren't really useful.
It then took about an hour to iron the new hem flat with about half an inch inward turn, hand sew along in a tacking way (the stitches not coming through the front), and ironing back the lining to match and sewing this along onto the back of the tweed.
For the sporran I simply cut a template from paper to fit the inner surface, cut the fabric to the template and glued it on to the sporran, cutting around the fastener with a scalpel. The top flap of the sporran was then covered and trimmed off.
This was a very inexpensive job to do, and allows a very ordinary black kilt to become part of a 'smart casual' look very easily. At this price, even with the need to purchase an inexpensive sporran each time to cover, I shall almost certainly be making more when appropriate jackets turn up at the charity shops. And it also helps the charities.

The photo unfortunately looks like the bottom of the jacket isn't level, but it is. I shouldn't have scrunched it up in the pose. Anyway, you get the idea.
Pete