K-9 time!  I made him deliberately a little banged up from his latest adventures.

Now, here's the process:

I drew out the basic pattern for the sides, the top, and the bottom on thin cardboard.  Then I liberally applied some tape.  In fact, the two remaining sides are made entirely of tape.

I used the accordioned bit of a bendy straw for his neck, and built the head in just the same way as I built the body.  I added panels to the sides and front.

I painted him all over with silver nail polish.  His tail is a metal headphone plug that I found on an airplane.

Now, of course, the easiest way to make a K-9 for cheap is to google image search for "K-9 Doctor Who Papercrafts" and then cut one out and fold it.  But since when have I ever done anything the easy way?