The DU Lounge

Two things come to mind.

The first is a box resizer. You can make smaller cardboard boxes from boxes that are too large, and they come out crisp. I often use this when shipping boxes. It has an arm that slides along the top of the box, and a little scoring wheel that makes fold lines - where to fold/cut to make the box smaller. It is an inexpensive, helpful gadget.

The second I had some years ago until it stopped working, and haven't been able to find another one - a solar operated fan to cool down your car when it is parked. It fit on top of a car window, snug up against the top of the closed window opening, and circulated air inside/out. It really worked, but I guess there may be issues with security, and getting it to be snug for all car window types. The prediction was that a solar operated fan like this would be built into car roofs, by the manufacturer, at some point, but I haven't seen that feature, at least on the cars I have driven.