If your target is soft enough so they don't pulverize on impact you should get several shots from each one before they're all lost. Spray them fluoro pink so they stand out more in the grass. If you buy several dozen, you may get them for only a few cents each. I have tried this and the only thing I found annoying was cutting the holes, but I didn't have any really good tools. Perhaps you could burn them through with a soldering iron?

If you are not going to fill the ping pong balls with concrete what are you using them for? Don't know what your objection to them is. Filled with concrete they fly beautifully.

You could merely cut them almost in half, leaving a little piece to act as a hinge, which would reduce the cost as they could be re-used.

C_A, I may be onto a reason for the relative lack of success. If I understand this correctly, you lay a sausage of cement across the lower half channels and then squish down with the upper half and roll. The sausage is of the same diameter as the rolling channels, i.e. the same as the final sphere diameter.

The volume of a cylinder 40mm diameter and 40mm length is 50265 cubic mm

The volume of a sphere 40mm diameter is 33510 cubic mm

So you are trying to roll too much cement, it can never form a sphere.

If you keep the 40mm rolling channels and use a 30mm sausage you will be rolling 28274 cubic mm of cement which is pretty close. There will be slightly more material than that since these calculations do not take account of the wall thickness between each rolling channel.

Is "project crocodile" going to be documented with pics and everything, like the giant pill roller, or is it so secret and mysterious because you´re planning to patent this contraption?

right now im tired and grumpy

Why dont you tells us what the h**l is project crocidile is?!?!

[quote author=curious_aardvark link=1206889228/15#23 date=1211811429]
I can't envisage any major problems, but then you never really know till you try these things.
If it does work it'll let me mass produce ping pong ball sized cement balls, with pretty good precision and much speed. It's a dead simple idea just don't know if it'll work :-)
[/quote]


(scratches head for a second and grins)

Sounds like I was thinking the same thing you were, bud.
The only problem I see is the mud viscosity making things difficult to press.

Remember leverage. :)

bumpity bump bump - for the newbies