So, I went to see a band in 2019 but the merch table had no shirts in my size, figured I would buy from their website later. Website also didn't carry XXL and they've been sold out everytime. I thought about making my own but have many questions.

is it wrong (morally)?

I understand about copyright & intellectual property (I've reached out several times to artist but no response). My intent would be to get the shirt made & also send money to artist (royalties).