If you're going to be fussy, this is not a frisbee, since it does not involve the famous pie-tins.
It is, however, eminently modifiable, decorateable (is that a word? It is now.), and suitable for using indoors.
Even better, it can be educational (see the last step).
Print one out with your corporate logo, then if you're caught playing with one of these at work, tell them you're using your initiative and testing out a potential marketing tool...
Step 1: The template
As is my wont, this is made from a single A4 sheet, this time of light cardstock (about 160gsm, if you need to know).
I have included a PDF drawn up from a scan of my original sketch, including two versions - one decorated, one plain and awaiting decoration by your good self.
Print out the one you want, then cut it out, including the seven rectangles at the top.
(If you are going to decorate your frisbee by hand, do so before you cut it out.)
Step 2: Score!
All the dotted lines of the template need to be scored - with a ruler, run the edge of a pair of scissors, or a dead ball-point pen along the lines so that they are easier to bend.
Step 3: Up hill and down dale.
The shape of the frisbee is formed when you fold the scored lines.
The outer ring of lines needs to be mountain folded, and the inner ring of lines needs to be valley folded.
As you do this, the pacman-like gap in the template will close up, allowing you to glue the tabs on one side to the straight edge on the other side.
When gluing, use whatever suitable glue you like (glue-stick, "white" glue, even wood glue), just don't use a vast amount, or your frisbee could be unbalanced.
Step 4: Weight a minute.
Frisbees fly more stably when there is more weight near the edge of the disc (yes, I know this isn't a disc, but it's easier than continually referring to the regular heptagon).
Cut out the seven rectangles from the template, score the dotted lines and then zig-zag fold them up and glue them into small blocks, which you then glue under the edges of the frisbee,
If you are using a glue that needs time to set, clothes pegs make good mini-clamps.
You will see from the photos that I used pairs of small neodymium magnets to clamp things in place while the glue dried. Do not do this! I spent more time than is probably sane getting the blasted things in the right place, unsticking them from their neighbours, my tools, my watch... Seriously, use pegs.
Step 5: Done!
Once the glue is dry, you're ready to go.
I won't tell you how to throw it (if you didn't know, why did you make it?), except to say that it does not do well in a forehand throw.
I have no idea why, maybe I'm just no good at the forehand grip...
Step 6: The educational bit.
It was two years after first publishing this project that I realised it had genuinely educational potential for maths lessons and Cub or Scout meetings.
I added an extra sector, making the final Make an octagon, and added the start of a compass rose - the kids can add the rest, including the navigation bearings, then colour and make it up as they like.
This will help them learn the compass points, angles and bearings, suitable for KS2/KS3
The model in the photos is green because my school was closing down a few days after I created this - we'd run out of white card, and were working our way through the remaining coloured card.