Spud, don't you have anyone (woman) to help you with that? I would buy matching or dark rib trim because it has to be gathered slightly to fit the bicep otherwise it will just stretch weird. My advice, buy a sweatshirt and 3/4" to 1" wide ribbing at Walmart, take it to a local cleaners that has a sewing service. Really an easy thing to do. If you want do more than one because it will cost less per item in the long run and when one is in the wash, one is available. That is if you really want these. I've never seen a short sleeve sweatshirt and I've worked for a screenprinter for all kinds of shirts.
Hey OuMoose, good for you! I noticed my son is really good at sewing. He learned in junior high-required course. He sews all his camouflage bags, rips in his paintball stuff so he got really good at it. TW