Yes it is! So long as the power stays on, all is well.

You get a fairly big (birthday-party balloon sized), helium-grade rubber balloon and fill it up with water, then blow a little air in as well and seal it up. Then, stick it outside in very cold weather (like we're going to have for the next few days). Leave it out a good long while--but not too long, or it will freeze solid. I left this one out for about 12 hours. If you get the timing right, enough of the water will have frozen to make a good thick shell, but in the center it will still be liquid, and where you blew in air will be a thin spot where you can break through the ice. You do that, pour out the remaining water, and you have a balloon-shaped, hollow ice circle. (Also you cut off the balloon, obviously, so all you have is the ice.)

Yes, you might stay the night and come back a hundred years later--if you come back.

Thank you! If you get a very cold snap, you can make one too.