Light covers that go over a light bulb. One time use only though. You have to break the glass globe once the concrete has set.

Thanks clc. I had thought of that as I have seen it posted before. I guess I need to look at thrift shops for those old white opaque globes. Too bad they would only be a one time use item.

I have seen plastic molds you can get to make 16" snowballs, and wondered if they could be used to make hypertufa spheres. I imagine you would have to fasten the two sides together very tightly (maybe use clamps?) and make a hole in one side to pour the 'tufa mix in, and it would leave a seam, but that could be scrubbed off. If the plastic is sturdy enough, they could be used over and over!

Here is a link that might be useful: snowball molds

Hmm, I wonder if you could just make halves and then glue them together after the fact with more tufa mix? Then again if the layers were smooth enough on the halves, you might be able to silicone them together and then add more tufa at the joint to mask the connection? Certainly something to think about. One thing I wasn't certain about was whether you get two of the molds when you order one or is it one set of molds?

I think you get two halves to make a whole sphere (or snowball). A 16" sphere would be very heavy, even made with hypertufa instead of pure cement. I'm wondering how you could add a ball of some sort to the center, to make it lighter.

I got some nice two-piece molds from History Molds. They have them in 3 sizes. You are right that solid, spheres are heavy, but once they dry they aren't too bad and they are sturdy.

How I make them is make one half and stick some thin rods in -- maybe 3 and put them around the edge in case someone wants to bore a hole through the center to make a fountain;

When that half has cured a couple of days, unmold it then fill the emply half of the mold, place the partially cured half with the "sticks" onto the wet mold and let it cure. The two pieces hold together well and you don't have to worry about glue, etc. Just smooth out the seam and you've got yourself a sphere!!

Don't see why a half of a ball (so you would have a flat surface)smaller than the diameter of the mold couldn't be filled with something to make it stable, put into the mold and the tufa put in around it, with the "sticks" near the edge to help hold the two pieces together; or just pack the mold like you would any other kind of mold, leaving the sides thick enough to be strong and hold the "sticks"

I use a child bouncy ball My Spheres are hollow and do have a opening at the bottom which you can close up if you want . I just use the ball as my mold and then let the air out once done pull it out of the now harden sphere and I can use the ball again . I usually leave a opening in mine as I use most of them for planters however I did see some recently where they were complete Spheres painted up as Baseballs and basketball, soccer ect that were very cute and I have though about doing that . Just do a search on Hollow Spheres there are several web sites that give complete instructions ......Good luck

Thanks for the ideas all. Appreciate them very much!

Do a search for "History Stones".