Products I fulfill from my studio in Ireland:
Originals
Prints
Zines
Stickers (all excl. the 'Capybaras with Jobs' Sticker Sheet)
With the introduction of Tariffs for shipments to the USA, additional duties apply for any item exceeding 'letter' sizing - meaning original artwork, prints sizes A5 and larger, and zines.
"For businesses posting  ecommerce goods of any value, taxes will be determined by the value and origin of the goods being posted, and must be paid by the receiving customer before the item leaves Ireland. They will continue to use An Post’s existing data capture systems, and will provide additional contact details for their receiving customers in the US More details and support are available at an post.com/USA"
A valid e-mail address is required for AnPost to contact you and request payment of applicable tariffs before the shipment leaves Ireland.

All other items are fulfilled through Fourth Wall via Print on Demand service. 
In case the product is not fulfilled in your economic region (i.e. you are in Canada and the product is shipped to you from the USA), customs and other duties may apply on / before receipt - as it has been previously in alignment with international trade agreements.