There are several T-shirts
around using Klingon letters and phrases. Unfortunately textiles are offered on many websites, supposedly showing klingon sentences, but are full of mistakes. Others may be be quite well. Some of them are licenced products, some were created by designers, and some originated at Klingon language meetings, like the KLI
's annual meeting the qep'a'
or the qepHom Saarbrücken
This page summarizes a list of pages about existing T-shirts.
Links about T-shirts