For the past four months, my son's been working on his first RPG scenario. He based it on Lovecraft's At the Mountains of Madness after reading first the graphic novel and then the story itself.
Using Fimo, tin foil, cocktail sticks and hot glue, he made all the monsters himself. He also painted up miniatures for the player-characters (in a single afternoon after school!) and made floorplans from cardboard, white glue and loo roll. He drew designs on index cards to show the carvings on the complex's walls.
This Sunday, he ran the game for four friends. It seems to have been a hit, and he's planning to repeat it with a couple of other groups of friends. The giant penguin - in lieu of the group of merely large sightless albino penguins in the story - was my sole contribution to the set-up. It's a Hobbycraft papier-mache shape with some added extras in Milliput.
I'm sure we'll find ways of recycling the monsters in other games. There are three Elder Things:
The Whistler in the Darkness (an orginal creation):
A captive Mi-go:
And - of course - Shoggoths:
My son also drew this to encapsulate the scenario:
All in all, it somewhat outstrips my efforts at a similar age; those were largely confined to graph paper.