Don't try and carry it.
Ask UPS, FedEx, DHL - you should find someone that knows how to do it safely / legally. I think - but I am not certain that there are more tests carried out these days on the packages including X-Ray, sniffer dogs & some form of pressure testing & for good reason.
I have heard stories of people couriering in 'paint type materials' by hiding them within (the inside of) tins of other materials such as fruit syrups - quite horrific stories actually and I wonder if these things are ever found out - I hope they are.