I found this really great blouse at a thrift store. The sleeve elastic was pretty wimpy when I purchased it and then died after a couple more washes. So I ripped it out to replace it.
The elastic was not a very good quality. But it was interesting to see that the elastic ends were butted up together and stitched. This is in contrast with overlapping the ends and stitching the ends together, which would certainly be bulkier.
Here is the fixed sleeve. I had to substitute with 1/4 inch elastic because that is what is in my stash. It worked just fine.
I love this blouse so much that I will probably take it apart and trace it off to make a new one. The trickiest part will be replicating the elasticized gathered sections on the yoke. The neckline slit was not finished with bias. Instead it is a narrow, rectangular facing. I imagine it would be easier to do.