I would like to know what type of material to practice on other then alumunium, to keep cost down on my 3 axis cnc mill?
Any advice would be greatly appreciated!

Thank you,
Jim Mill

try using 12L14 leaded steel, cuts really nice!
also try plexiglas, it comes in all thicknesses too

mdf would work well , you can glue pieces together to get larger stock size if you need ,one sheet is cheap and would go a long way
safe on tools as well

Widgitmaster and Detsap. I thank you for your quick reply to my inquiry.
Is mdf (mild dentisy foam ) ? If I'm in error please correct.
Again, Thank you,
Jim Mill

MDF - Medium density fibre board - a man made material used as an alternative to wood.

Bar soap for small parts, 4x4 wood chunks glued together for big "billets".