This would make a great Christmas gift. It is currently selling for £19.99 on Firebox.
The Sun Jar is a frosted glass jar with a solar cell inside that charges a battery (when the jar is left in sunlight) to power LED lights inside it. When switched on, the jar will automatically start to glow when it gets dark.
Original design by Tobias Wong
Glass jar, solar cell, battery and LED lights
While Sun Jars do make excellent outdoor lighting during the evenings, it is recommended that when not in use they should be stored indoors on a sunny window sill.
For best results, please leave the Sun Jar switched off whilst charging. Simply switch it to the on position when you would like it to glow. This conserves battery life and will leave it to illuminate when you need it to.
There are mixed reviews on Play, but the Firebox reviews are nearly all very positive. Seems like a good deal to me!