A 7-in-1 multitool in credit card size (although it's rather thick...)
Tool set:
- 12mm, 10mm, 8mm, 6mm, and 3mm hex nut wrenches
- 6mm screwdriver bit holder
- Funnel
- Scraper
- Bottle opener
- Whistle
- Ruler (metric)
Tried to fit as many functional utilities as I could on something that could be made of plastic.
Ruler is metric; each tick is 0.5cm and each tick width is exactly 1mm.
Whistle is surprisingly super loud (it's on the opposite side of the ruler). Scraper is useful for your car during winter if you don't otherwise have another scraper for ice/snow buildup. Funnel is useful for precise liquid pours, and the screwdriver bit hole in the one corner is useful as a backup. (Alternatively, the bits also fit into the 6mm hex nut wrench)
Pretty useful little tool to carry around. And if you get it made of plastic, it won't set off metal detectors! (Great for overseas travel)
Get in plastic for this reason, and that it's the most lightweight option; or get in metal if you don't mind the extra weight and you want it to last for ages!