Can you use a cnc machine to make something like pistons

Basically just asking what the title says, i have access to a cnc machine and was wondering if i could use it to make piston heads istead of buying?

Do you mean cylinder heads, or the pistons? If it's cylinder heads the answer is no, not possible to machine the coolant passages.

If it's the pistons, it would be difficult to CNC machine durable pistons. There are some major problems. The first problem is programming the piston shape. The second problem is obtaining the correct aluminum alloy. The third problem is properly heat treating them.

There are many videos on the internet that shows the process of manufacturing pistons. I recommend that you view a few of them.

what about connecting rods, do they require any special type of heat proofing or metal?

Yes

okay, thanks

Pistons are also machined from forgings. The molecules are smooshed together tightly and with the grain oriented in a specific direction. That metal is stronger than just a billet of the same metal.

After machining and heat treating, they are weighed and matched in sets. Do to manufacturing tolerances, not all of them come out weighing the same.

For connecting rods, the holes on the ends are more precisely made than you'll get off a CNC. If that wasn't the case, then you'd be able to mix and match the caps and it wouldn't matter.