For no real reason, I decided to build a paper plane that's a bit more involved than a simple dart.
You'll see a mix of images in the write-up; those built of graph-paper were the prorotyping stage, and those built of plane paper use the template I drew up for you to build your own.
Step 1: Needful Things
The Prism has only four parts - fuselage, wing, wing-support and tail.
So, the PDF file has six copies of the template on it - enough to make either a small fleet, or lots of mistakes.
You'll also need ...
...something to cut your paper (if you're using a knife, you'll need a cutting mat and a metal ruler as well).
...something to score the paper
...glue (I used a glue-stick when prototyping, but switched to a liquid PVA woodglue for the final model)
Step 2: Cut
This step is easy - cut out the pieces.
I used a sharp knife and a metal ruler to make sure the cuts were straight. You can use scissors, you just need to be able to cut straight and tidy.
Don't throw away the scraps from around the template, you'll need them later.
Step 3: Score & Fold
"Scoring" is a way of ensuring creases happen in the right place.
Some people use an empty ball-point pen, or a blade pressed gently.
I used a pin, dragged at an angle along the edge of my metal ruler.
Score all the dotted lines, make sure they crease, and fold the tail piece in half (it has no dotted line across the middle.
Step 4: Fuselage
When you score and crease the fuselage piece, it looks like it will be a square cross-section.
Smear glue along one long edge (fill the space between the dotted line and the edge of the paper), and you can glue the fuselage into a long triangle (and now you know where the name came from!).
Step 5: The Wing
Fold over and glue down the narrow part of the wing - the folded edge will add stiffness to the leading edge of the wing.
Do your best to keep the wing straight as the glue dries (something I found much easier with the liquid glue).
Step 6: Fix the Wing
The wing support fits around the fuselage, in the fourth centimetre from the front of the plane. (measure 3cm along, and glue on the support - the back edge of the support meets the centre of the fuselage).
When the glue is dry, add glue to the small flaps at the top of the support, and centre the wings on the support.
The top creases of the support will be about 2.7cm from the wing-tips.
Step 7: The Tail
Fitting the tail is simple - just glue it around the fuselage at the back of the plane.
Step 8: Ballast
Although the structure of the Prism is finished, it is not ready to fly.
Go on, try it if you don't believe me.
You need to add mass (ballast) to the front of the plane. You could use a small blob of modelling clay, but I prefer to use paper.
Remember that off-cut scrap from step two? Cut a piece roughly 1x10cm, and roll it into as tight a cylinder as you can. slip it into the nose of the plane and you're done. You could add a drop of glue to hold it in place, but I find that the friction caused by the paper trying to unroll is plenty to fix it in place.
Step 9: Trim
It is extremely unlikely that your Prism will fly perfectly on the first throw.
To change the flight of the plane ("trim"), you can twist and curve the tail and the wing-tips.
Twisting the tips of the tail affects the left-right path - play with these to get the flight straight.
Curving the tips of the wings affects the lift - adding a slight downward, frown-like curve can extend the glide time dramatically.
Step 10: Done!
That's it - enjoy building your own Prism, modify it, hack it etc, and post pictures of your planes in the comments.