In terms of actual construction, the tent was much simpler than the blockhouse. In terms of design, it was more complex (but only slightly so).

Having some basic knowledge of drafting is very handy when designing something like this. I knew nothing about drafting until a co-worker who used to be a sheet metal engineer showed me how to translate a drawing into a plan.

The tent in the photo appears to have a square room but a round top. I decided right off the bat that matching that would be too complex, and that I would make everything square. I also knew that I wanted to be able to remove the tent roof so I could put figures inside--that meant no ropes. And I wanted to be able to put four figures inside. My figures are mounted on 3/4" round bases (pennies, in fact), so I decided the tent should be 1 ⁷/₈" square.

The tent would have three pieces: the walls, the floor (glued in to keep the room square), and the roof. I would make it from folded cardstock. The walls and floor were cut from a cereal box, and the roof from a piece of manila file.

I started with the drawing shown in Fig. 1.  From this simple drawing, I could get all the measurements I needed to lay out the plans.

The walls were very simple, just four sections side by side, folded at the corners, with a gluing tab at one end and gluing tabs at the bottoms of each wall section (for attaching the floor). I also cut out the doorway before gluing the walls together.

The roof is also very easy to lay out, but only if you know a couple of simple tricks. Each section of the roof would be a triangle. The trick is figuring out the dimensions and angles. The information is all hidden in Fig. 1. The height of the triangle is the dimension A-B. The base of the triangle is the dimension B-C.

With those two dimensions, my compass, and some high school geometry, I soon had the length of the triangle's side. With my compass set to that dimension (call it A-F), I drew a circle on a sheet of graph paper. I made sure I had the center point marked. Then I reset my compass to match dimension B-C from figure 1 (F-G in figure 2). Starting at a random point, I marked off arcs of the circle, each one defining a tangent that had the length F-G. With four connected tangents marked off I just connected the dots. One of the triangles had to be shortened to make the section over the door, so I reset the compass again and marked off the dimension A-D and A-E. After adding a glue tab, I was left with Fig. 2.

Once the drawing was complete, I had to transfer its dimensions to the manila card. The best way to do this is with the "poor man's photocopier." Place the drawing over the card and then use a pin (in my case, the sharp point of the compass) to gently poke through the drawing into the card at each intersection point. Then connect the dots on the cardstock (if you're cutting with scissors) or just lay down your straightedge from point to point (if you're cutting with a an X-Acto knife). Also, be sure to score every line where the card will fold. You want to create a crease, but not a tear or a cut. The best tool for scoring card is an old ballpoint pen that has run out of ink. If I don't have a dry pen handy, I often use the blunt tip of the can opener on my Swiss army knife (it's not like I ever need it for opening cans, and it's always in my pocket).