This subject comes up pretty often and usually baffles me as to why everyone is afraid of international shipping... that said, I must say that my background was in international shipping before I retired and I've been out of the business about 6 years and things were changing regularly even when I was in the business, so I know there have been a number of changes in the past 6 years... however, I would not hesitate to ship anywhere in the world today if I made the sale and the foreign customer has completed the payment.... I would hold materials until the payment has cleared, but I also do the same for domestic shipments.
Shipping to Canada (and Mexico) fall under the NAFTA rules (as well as some of the south American countries) which are fairly simplistic to do... the postal forms are relative simple and easy to fill out.... USPS postal service is generally the least costly, but there could be costs at the destination country that will likely be passed to the consignee and the shipper may never see. Most postal services have an automatic clearance procedure - unless you have declared a higher value... different countries will have different levels of the declared value... a pen or pen blanks will likely go through without problems... you could run into difficulties with certain types of woods in some countries but that will fall under their equivalent of our USDA (department of agriculture)... as an example, when we shipped to Australia, their DA required that any woods with bark be either fumigated or not shipped... as a rule, we fumigated every shipment to Australia... some shipments especially larger shipments of woods will require a phytosanitary certificate from the USDA... it's unlike that we as small time shippers of pens and blanks would ever run into that... the large wood importers in the USA have the same problem... if the woods arrive without proper certification, it is either seized and destroyed or held until it can be certified and/or fumigated or some other procedure that USDA and USCustoms deems safe and proper for importation into the USA. Believe it or not, our own US Customs has rules and regulations that makes it difficult for some importers to bring materials into the US... in some cases our customs service is more difficulty to work with than some foreign customs.
If I were shipping to some third world where the mail services are iffy at best, I would probably opt for one of the courier services, Fedex, UPS, Msas, DHL, etc.... there are more, but I've forgotten the names of most... as an international manager, I used Fedex and DHL almost exclusively... Domestically I liked FEDEX and internationally I use DHL... especially for all of my banking documents. Otherwise, on smaller packages, I would stick with the good ole' USPS.
That's just my take on the international shipping question.