I love these glass frame pendants. They're inexpensive, versatile, and great for paper-cuts. You can cut any shape you'd like, but I've included steps for cutting this paper airplane.
Step 1: Materials
Glass frame pendant
Straight edge or ruler
Step 2: Template
Trace the center of the frame then around the glass. This will allow you to see how large your paper must be as well as what will be visible.
Step 3: Draw a Plane
Follow the steps in the image to draw your paper airplane.
Use a straight edge or ruler to keep your lines straight.
Step 4: Bulk up
Make the lines wider.
Again, use your straight edge for this.
You need the lines to be wide enough that you can cut around them and not have them tear.
Step 5: Cut
Cut out inside the lines with an X-acto.
Flip your paper over.
Step 6: Marker
Use the straight edge to draw the lines again with the black marker.
This step is optional of course, but I liked it better with the lines.