They need to be smooth on the inside.

I can\'t wait until hermit crab conventions have \'The stupidest looking shell contests\'.

Sammy shuns shotguns shells in search of synthetic sea shell substitutes? seriously?

Your making shells for hermit crabs out of plastic... AHHHHHH!!!!!!!!!!!

More exploitation of sentient creatures :( Instead of encouraging the cruel and speciesist \"pet\" industry, PLEASE JUST LEAVE THE CRABS IN THE WILD WHERE THEY BELONG!

I think it\'s a great idea if it works! There\'s many great things you can do with 3Dprinting! @GROWit3D

1. Katia Luto - out on the wild, hermit crabs don\'t have popcorn, and they love popcorn. They also love not being eaten, which also happens a lot more in the wild.
2. Forget these printed shells - now I want a hermit crab with a shotgun shell!
3. I\'d also like to know what beaches the crabs with shotgun shells are found on, as I would like to stay far away from those beaches.

Instead of using this technology for the pet industry, scatter the printed shells in the areas that the wild crabs can use them. Then they won\'t have to resort to the shotgun shells or bottles.
And, to alcalde, re. your point #3, the shotgun shells in question are the already spent ones that are empty. The crabs won\'t shoot at you ;-)

I think some made in the shape of little Air Stream travel trailers would be a sell to the pet industry.

\"Sammy shuns shotguns shells in search of synthetic sea shell substitutes? seriously?\"
I can\'t even say that once at normal speed, let alone say it fast five times. WIN!