PVC works fine, but you do have a problem with your setup. It looks like you have just 4" runs from the DC to all your tools which is very bad when it comes to getting the most out of your DC.
What size DC do you have and how large is the intake on it? If the intake is large then 4" you really should rethink you ducting, it may cost more money but it will be worth it. We fitted ours ( home shop) last year from all 4" to 8",7,6,5 and finally 4" at the tools and wow