Just look up T5 endcap. You attach the 2 encaps on each side to a reflector and wire it and that's what a light is! I really don't know much about a DIY light, but I don't think it would be too difficult and marinedepot and prob. other online stores have the parts for it. I don't know if that's all there is too a light fixture, but that's all I know. It's fine, ask away! Better than not asking at all and making mistakes/wasting money.
“Success is walking from failure to failure with no loss of enthusiasm.”
- Winston Churchill