I asked the same and got 4 expensive used balls from a pro shop and made pens for them. These were solid balls no filler except for the counter weight so I got a lot of material. This is a link to the library for cutting up balls with a skin type cover:
http://content.penturners.org/articles/2005/cuttingbowlingballs.pdf and this is a link to the balls I cut and try to stay away from particle balls they will tear up tools and the others will dull tools quickly so be prepared to sharpen them:
http://www.penturners.org/forum/showthread.php?t=71017&highlight=bowling and this is how I cut mine up:
http://www.penturners.org/forum/showthread.php?t=69207&highlight=bowling and finally what I finally did to save bandsaw blades:
1. I used the small battery powered circular saw to cut as deep a groove around the ball as I could.
2. Using a small hammer and a nail prybar I put this in the groove and went all the way around pounding on it till it split (sometimes the weight comes loose) and then repeat the process on the halves.
3. Using a hammer pound on the couter weights until they fall out (this stuff destroys a blade just by barely cutting into it). Any residue I used a small blowtorch to heat up the couterweight material and then chip it out with a small tool.
4. Now comes the part where you try to get the needed blanks cut before your blade goes dull on your band saw.
I wish I could help more but I have 2 medium flat rate boxes full of this stuff.
If you do a search here just type in bowling and look for my user name and you can see the fun I had and wear a mask and eye protection this stuff is dirty to cut.
Jerry
