You can go to USPS and get a list of international prohibited items. The only thing close is water based paints which can be shipped but need to be contained in a seal-able bag or container. If you put it in a zip-lock bag, it should be OK : )
https://www.usps.com/ship/shipping-restrictions.htm
http://www.postoffice.co.uk/mail/international-what-can-i-send
Susan