http://www.kleinbottle.com/index.htm

The Acme Klein Bottle Company

"At last, Acme has conquered topological and engineering frontiers to manufacture genuine glass Klein Bottles. These are the finest closed, non-orientable, boundary-free manifolds sold anywhere in our three spatial dimensions.

These elegant bottles make great gifts, fantastic classroom displays, and inferior mouse-traps. With its circle of singularities, an Acme Klein Bottle can be said to exist inside of itself -- especially handy during time-reversals."

See also the calibration options:

http://www.kleinbottle.com/calibrated_klein_bottles.htm

Now -- Calibrated Klein Bottles!

"In response to underwhelming customer demand, Acme is pleased to introduce calibrated Klein Bottles.

You need never doubt the volume of your Klein Bottle, now that Acme provides fully calibrated Klein Bottles. To determine the volume, simply glance at the easy-to-read graduated scale.

Best of all, this calibration service is FREE! With every Klein Bottle, you'll receive a clear-vinyl calibration decal that sticks to your manifold. Just peel away the stiff paper backing, and then carelessly press the clear decal onto your bottle. No adhesive is required, so you can remove the decal during leapyears, should the authorities so require."

(Thanks to the Forteana list!)