Hi Dennis,
Thanks for your interest. I create the chips myself by casting the round blanks, cutting them into 4 along the length and then cutting the quarters into slices of around 3 to 4mm. It's very long winded but i think they are worth it and so do the guys that buy them.
I use a 1/2" x 24tpi bandsaw blade thats gives a nice clean cut. I have considered trying to just smash them up with a hammer but it is too messy and I find that irregular shaped pieces can cause air bubbles to get trapped when doing the big cast.
Hope this helps.
Regards
Eric...