Raspberry Pi + special OS with fun web apps and instruction manual
Smart lava lamp
lava lamps take about 1 hour to start working and need to be shut off after 6 hours
E-paper PDA (calendar, clock, alarms, address book, MP3 player, flashlight etc) that also serves as a offline RSS reader / pocket size ebook (use USB-C to charge/sync)
Heated dakimakura
Like an electric blanket, but more weeb-friendly. Good for the winter.
Tower of Hanoi flashcard set
The classic recursive math toy, but one can insert cards with things like constellations, moon calendars, conversion tables, etc into clear plastic disks. Pragmatic.