Monster Cars is a good one actually, it could be popular. I am at a bit of an empass, myself. I am tring to design bitmap t-shirts using 3D software, which is easy enough, but I am struggling for ideas. I thought more variety in big jungle animals might be nice? Snakes, cats, elephants, etc? I mean everyone in 3D wants to make spaceships, but I'm not sure there's such a market for those. If you ask people what their favourite animal is you usually get a positive response.