FIFTEEN t-shirt designs needed

Hello

I am putting together a large portfolio of t-shirt designs. Target is 500 designs over next six months. There is total creative freedom with the exception of following rules:
1. No politics or religion.
2. No copyright infringement
3. Easy to print (screen printing not digital).
4. Two designs must be about water conservation. 1 t-shirt = 2700 litres of water = 3 years drinking water for a person.
So the tagline is : Don't buy. Rent.

Please bid for 15 designs. I am trying to cast a wide net so we get variety. Good designers likely to get repeat work.

Thank you.
Toshio Moretti