I have a number of older metal t-shirts, some more common and some from tours. They no longer fit me (mostly size M and some L) and I'm debating what to do with them. I'm not expecting to sell them for much money, more curious to see what you do with your old shirts including those that are fairly worn out (faded, sleeves cut off, etc)? Also, if anyone is interested in what I have I can add a list to this topic if it gains traction. So tell me, what do you do with your old shirts besides boxing them up?

I collect shirts. There is definitely a market for them, with the older ones from popular bands going for silly money.
If the sleeves are cut, the value goes down significantly. Considerably more if they are cut on the waist like they did in the 80s.

I wear my shirts, even when they are grey. If I can't wear them, usually because they don't fit me anymore, I usually trade them. Sometimes sell.

I'd be interested to see a list, even though I wear XL mostly. You could find interest here but mostly the large trading/selling happens at ebay, tshirtslayer (site dedicated to metal shirts) and facebook groups. There are several.
Hope that helps!

It would be great if we could see pictures of your shirts

I appreciate the responses so far, I'll try to get a list together when I have time possibly this weekend. Most of the concert shirts are buried in a box I'll need to dig out from the closet. The more common shirts I have in a stack so can get you an idea of what I have. They are in varying conditions and I know how picky people can get on eBay even when you post pics and explain that. I figured I'd start here and ask the metal forums before I donate or ebay them, of course I'll give everyone a heads up if I post them.

Yes, there is a huge market for them. There's an Arckanum shirt on etsy for $80 right now. Whether or not it will sell is it's own question, but it's still there.

I know I'd be willing to pay for some rarer shirts.

You should check out www.tshirtslayer.com

"World's largest community of heavy metal tshirt and battlejacket collectors."

There's some cool stuff on there! I don't have anything that rare or unique to post, the 1st batch of shirts I'm going through are mostly non-tour shirts that I'm trying to sell.

Here's a link to some shirts, if this doesn't work let me know. Not sure how to post multiple images without using a pic hosting service.

https://drive.google.com/drive/folders/1mph8SMVcxZzzSiEFB0OLBW9xwLy1knrX?usp=sharing

eBay listings are up for the first round of shirts. Please check them out under my username: spiritinblack82 or follow link to 1 of the listings here: https://www.ebay.com/itm/296381229665

I have a couple of friends who might be interested in a couple of your shirts. Would you ship internationally?

I'm not planning on shipping internationally at this point. Thanks for your interest in the shirts and if I decide to sell outside the country I'll update this post.