If you are looking for an excellent gift, Inpro Solar 24ct Gold Plated Stirling Engine will be a perfect option for you. This micro Stirling engine is plated with 24-karat gold, which invented by Robert Stirling in 1816 as a hot-air-engine. It uses a hot heat source (a small alcohol burner) and cold heat sink to expand and contract air in a sealed cylinder that moving the piston up and down.
The Inpro Solar was founded in 1981 at the beginning of the solar technology revolution, and all their products are made in Germany and make excellent executive gifts. This device comes with solar cells that are encapsulated within a flexible polymer for space applications. It’s an excellent gift for ages 14 and up.
If you need one, you can buy it from Amazon.com for $399.99.