This box was originally made in smaller dimensions. I found it on Linda Parker's website www.papercraftwithcrafty.co.uk
I needed a larger box and loved this design and decided to modify it to work for what I needed. The reinforcement pieces are necessary for the larger box, because the cardstock is lighter weight due to its ledger (tabloid) size. If you used heavier weight cardstock in the ledger size (11"x17") you could omit the reinforcements. The dimensions and cuts are in the video; to insert them you would simply glue to the bottom of the base on the inside of the box, then glue the side pieces inside the box to the squares adjacent to the bottom.
Enjoy the video and let me know if you have any questions about the project. Until next time...
Linda Parker's original project can be found here Year of Cheer - Clutch Bag Style.