In collaboration with Toronto's Kingbridge Centre and Killdee Scientific Glass, Acme Klein Bottle company has created the world's largest Klein bottle [wiki]:
The Kingbridge Klein Bottle is 1.1 meter tall, 50 cm diameter, and is made of 15 Kg of clear Pyrex glass. (For non-scientists, that's 42 inches tall, 20 inches across, and 35 pounds)
With 6mm thick walls, it has the same smooth shape as Acme's Classical Klein Bottle. One sided, boundless, and mathematically nonorientable. It tickles topologists and amazes visitors.
It's the size of a 5 year old child. A ferret can climb "into" it.
It's been a nontrivial glassblowing project. Indeed, very few glassblowing shops could handle this job. (One glass blower said, "Too scary for us!")
Link - via Unique Daily