comments:
Looks like you have a generic fastener in there already. Don't worry about going OEM. They are the little plugs that expand with an inserted plastic screw and they strip out pretty easily. May as well just get a kit of cheapies. They just won't match the color perfectly. https://www.amazon.com/GOOACC-Retainer-Plastic-Fasteners-Chrysler/dp/B07L6FJGR4/
Everybody says jump pack, and I agree. I have been stranded several times just because I left the headlights on by accident. It’s also great for charging your phone. The other times I’ve been stranded we’re mostly other electrical problems. So I’d add a decent auto-ranging Multimeter. Some regular jumper cables too. A 1/2 inch drive socket set, especially the metric sizes, the inch sizes will be mostly dead weight for fixing the Element. Maybe throw in an extra 10mm and 14mm socket too. 17 and 19mm are also very common. I say that because sets that have 10mm might not include 19mm. Tire inflator. And a patch kit To make your kit a little more classy and not mess up your fasteners:Get a JIS screwdriver.The special pliers for plastic push pin clips on the body. Some extras of those little plastic pins too, and some non-marring part bars.
Get a cheap assortment of fasteners and find the closest match to replace the broken/missing ones. If you're near a Mitsubishi dealer you could go to their parts counter and buy the exact OEM fit ones if you're a perfectionist. The zip tie fix will work pretty well, but they can wear out eventually. I'd at least use outdoor rated zip ties if you do that.