My car needs a new alternator and "serpentine belt" so I built this nifty cart for my bicycle to do the groceries with in the meantime. It took a few design revisions before I made a hitch that would stay hitched.
I'd been just carrying stuff in a back pack but things like a loaf of bread or eggs that don't travel well that way.
I looked into getting a baby trailer but those don't hold much and they run about $180 on ebay. This cost me only $20 for some metal rods and fasteners since I already had the scrap lumber around and some wheels from a non-functional lawnmower. I have many non-functional items around here.
It's not light. I'm sure it has increased my 0-60 time.