materials:
-Styrofoam pipe insulator
-masonite
-2x2" or 1x3" (I used 2x4" and could easily have gotten away with something smaller)
-bubble wrap and paper to protect the painting's surface
-screws
1. Cut a slit all the way down the pipe insulator. Fit the edge of the painting into it and cut off the extra, making sure to sufficiently cover the corners . You don't want any crushed corners!
2. Protect the surface of the painting with bubble wrap and I put an extra paper on top, just to make sure.
3. Put the foam insulator over the bubble-wrap, and make sure to get all around the painting, overlapping on the corners. Tape the corners so they stay put.
4. Next, we're building the crate. Cut your 2x2" or 1x3" to fit around your insulated painting. The foam will add about 1-2 inches on each side so take that into consideration when you're planning and cutting. Put screws into the corners, at least 2, 3+ is better for larger pieces, depending on your wood size/thickness.
Look! All snug! You won't want your painting wiggling around while it's getting jostled in the mail.
5. Once the frame of the crate is done, screw your mastonite right onto the wooden frame. I made a mistake on mine, forgetting to take into consideration the extra height of the pipe insulation (but I did it on the width!). You should screw the masonite down securely every several inches ALL THE WAY AROUND, not just on the top and bottom like mine. Oops. I know better for next time!
6. The customer bought a few smaller pieces as well, so I included the smaller pieces on paper in the back of the crate, in an envelope.
7. Then I screwed the top of the masonite on and wrote "To open: unscrew all the screws from this side" on the top of the crate, just to make it easier when they get the painting.
8. All done!
For those of you unfamiliar with shipping this big, my piece was 1'x3', and the crate ended up being (let's hope I can remember...) about 18"x42" and it cost a little more than $50 to ship, including the $1 per $100 insurance. I shipped through UPS.
Tip: Plan all the extra shipping and packaging costs into your artwork from the beginning so you don't see that big chunk come out of your profit. Good luck!