This was a present for a friend inspired by Finn Hudson's football uniform of the TV series Glee played by Cory Monteith.
Front view:

Back view:

Making your own t-shirt

So, one of the thing I do is painting t-shirts. Sometimes I do my own design and sometimes I copy the design from a t-shirt because I don’t like its cut or fabric. Anyhow t-shirt is from the latter group and is copying this one:

http://www.doubleagent.es/es/ropa/camisetas-12/1184_burn-out-t-shirt.html

And here is the process and the copy I made:

The first thing you must do is plan the design on the t-shirt - I cannot and will not trust templates - and the next thing is painting the design.

This type of t-shirts is very easy although drawing the little mermaid can be quite dificult. For that reason it is better if you use a little bit of water and different brushes. It is also very cheap because a plain t-shirt and textile paintings are cheaper than an already made t-shirt.