Yes, though the type of plastic doesn't really matter as long as the customs officers can see the innards of the gun.
I don't think they are neccesarily illegal. I would check with my local law enforcment to find out what the laws are locally before you purchase on of these guns. I know a great place that ships...
JC Surveillance will ship all Airsoft Guns to Canada. Also Chigun Hobbies.
Walmart