Burr

Kepler's Planetary Puzzle
Key Bunch
Key Trap (3D printed)
Kluvon
Knobula
Konstrukt
Krystal
Kubita
Kumi Six-Piece Set
Kumiki Desktop Puzzle
Kumikisaurus
L12 Burr
L8 Notchable
Lancelot
Lange Vinger
Lattice
Le CUBE d'H'
Letter L
Letterbox (Lohe)
Licorice Stix