Like Baja said, if you are doing it to have a "cheaper" board you don't have to do it...If you have some budget and just want to have some fun making one you can give it a go...Keep in mind that snowboarding companies have done a lot of research and developement through the years and have improved every little mistake they've made in previous models.
I'm sure that while making the snowboard and while using it you will notice a lot of points of improvements...mostly you will only be happy after the 4th - 5th model you've made after taking out all the little
errors in previous models

but like I said it can be a cool project to keep you busy and learn a lot out of it.
Here's an extra video of some guys I follow on youtube
Doing some really cool experimental stuff with snowboards.Might be interesting as well for the guys not interested in snowboards but more about experimental stuff with composites and manufacturing.Like the title says they upload a new video 'every third thursday of the month'