Please give me a good program for building your own machine embroidery patterns

And there is a free one http://www.freesierrasoftware.com...

I have it, but haven't even tried it yet.

Alice has given you a brilliant answer -)
I have Ped design 7,and generations bit I prefer my Embird and love it - :-)
I believe its a matter of which one you get used to using
Big hugs from London
Maria xx

There is no simple answer to this question. Different people use different programs and they are all different in price and functionality. There is no such thing as a good automatic digitizing program, you will have a big learning curve no matter which software you chose. You need to understand the construction of the a design and why it is put together in a particular way. I personally use Generations. I also have pe design next but I don't like it. Both of these are quite expensive programs up to $2000 australian each, there are cheaper ones on the market but I have never used them. Quite a few of the cuties use Embird, I have not tried it, but it seems to be popular.
I think there is a free one that you could get started on but I can't remember what it is.
Alice.