I carry stuff on my bike a lot, and I usually have to improvise. I occasionally use a duffel bag on my handlebars, but that isn't good for much. Yesterday I had a big box of VHS tapes strapped to the front of the handlebars, and when it hit the front wheel, launched ahead, and scattered tapes all into traffic, I realized that I had to act fast to get a better way of transporting stuff. I have asked another cyclist how he made his, but I can't find the simple parts needed.