Duct tape gets a lot publicity as the ultimate quick fix, but I think that zip ties deserve an honorable mention. These handy plastic strips are strong, they come in multiple sizes, and they leave no sticky residue. Any visitor to Farcical Farm will find them doing hard service by the dozens. Several are holding the gridded panels into the horse feeders, and I use them backwards through the lid latches to keep the feeders closed. They break easily if a horse gets hung up on them, but they last forever otherwise (until the goats chew them up, anyhow). When Titan learned to escape from the horse paddock through the big gaps at the tops of the tubular gates I zip-tied some wire mesh on to block them. There is small one at the end of the big spoon I used to stir horse feed so that I can hang it from a hook, and there are several large ones anchoring tarps to the back of our manure bins.
I have been closing both garage doors at night to keep Pipsqueak safe, but one of the four hook latches is so tight that I have hurt my hands multiple times trying to close it. Last night I used a zip tie to extend that loop by about half a centimeter and now it closes easily -- still secure, but not too tight.