Similar cups available here- some change with hot water, some with cold:
From Amazon: BUY NOW: Cherry Blossom Color Change Cup
Check out these other thermochomic physics toys
Cherry Blossom Sake Cups: ice cold liquid produces blue blossoms on the initially bare branch, but pour in a hot beverage and the branch fills with pink flowers! The designs at the bottom of these ceramic color-changing cups employ leuco dyes, thermochromic chemicals that have reversible forms, one colorless.
These stickers transition back and forth and can be used on many surfaces. Get some here:
From StemCell Science: BUY NOW: Thermochromic Saftey Sticker
Thermochromic Safety Sticker: the liquid crystal ester dye in this reusable sticker is calibrated to change color when the surface temperature exceeds 50°C (122°F)- that at which prolonged contact (more than 0.5s) will burn skin. Here the safety sticker is attached to a slab of aluminum and heated with a simple candle- it took about 3.5 minutes for the heat to distribute and bring the aluminum to the threshold temperature. When the surface cools the sticker again appears blank and can transition over and over again
Similar mood jewelry available here:
From Etsy: BUY NOW Liquid crystal jewelry
Thermochromic Liquid Crystal “Mood” Necklace: heat from a hand brings out the temperature dependent color change of the liquid crystal. The molecules of the liquid crystal change orientation and spacing during the phase transition from liquid (warm) to crystal (cool). The molecular configuration shift allows for different diffraction effects producing the color shift.
Liquid crystal sheets, thermochromic fun!:
From Educational Innovations: BUY NOW liquid crystal thermometer sheet
Thermochromic Chiral Liquid Crystals: the thin layer changes color as the molecules of the liquid crystal change orientation and spacing during the phase transition from liquid (warm) to crystal (cool).
Get one here:
From Amazon: BUY NOW Beam Down Star Trek Mug
Similar mugs here:
From eBay: BUY NOW Star Trek Heat Mugs
Thermochromic Beam Down Mug: Pour up some hot coffee and watch the crew of the USS Enterprise leave the ship and rematerialize on the planet surface with this color-changing physics mug. The color change employs leuco dyes, thermochromic chemicals that have two reversible forms, one colorless when wqrmed above a theshold temperature.