I have several ideas for a t-shirt design. However, I dreaded the upfront costs for printing t-shirts and holding inventory. Well it has been years since I look at this stuff. Oh! How times have changed. I found a company called Teespring that allows you to upload your designs and they do the fulfillment. All you have to do is promote your design, people buy it from the site and you collect a royalty. Amazon has similar site called Merch but it is by invite only. I applied and I am waiting on a response. I will upload two of my designs in the coming weeks.