Tags: plastic, acrylic, plexiglas
Many semiconductor manufacturers run sample programs that let you get small quantities of chips for very cheap or free. Some programs require a registered business contact. See this wiki page for more information.
Importing aluminum extrusion can be difficult due to restrictions. See https://talk.vanhack.ca/t/group-order-of-v-slot-from-openbuilds/1000/2.
Google Translate does a decent job. Refine searches by extracting keywords from the best results and running them through Google Translate again.
In general Point Roberts is closer and easier on Transit/Bike. Blaine is further but offers the chance to pick up a parcel as part of another trip. Tax info at CBSA.