Plastic
Bags
Plarn: Making Plarn
Crochet: Joining & Crocheting Plarn, Easter Basket, Handbag, Apron, Plarn Sandals
Many crocheted items/patterns can be replaced with plarn.
Knitting: Knit a bag from bags
Weaving: 'Traditional' Weaving (and how to make a recycled loom), Braided Rug (no sewing; braiding and ironing)
Fusing: How to Fuse Bags, No-sew Fused Tote, Fused Candy Bags
Food Wrappers: Candy Fused Plastic Bags, Pet Food Tote
Others: Pet Leash
Plarn can used for other fiber crafts, such as Macramé, Nålebinding, weaving
Plarn can also be made out of bags used for fresh fruits and veggies, as well as bags your newspaper comes in. Shorter sections of bag means more knots per foot, and would be better for knitting or crocheting than coil basketry.
Bottle Caps
Bottles
Inspiration: Bags, lights, notebooks, baskets & more
Individual Size: Stitched Plastic Ring, Spherical Ornaments, Bottle 'Flower' Curtains, Apple 'Boxes', Fabric-Covered Bracelets, Milk Bottle Ghosts
2-and-3-Liter: Self-Watering Seed Starter Pots, Plastic Bottle Birdfeeder, Cherry Blossom Stamper, Rustic Lamp, Plastic Loop Earrings, Shaggy Lampshade
Bottle Bricks, Build a House with Bottle Bricks, Sushi Mat Vase, Christmas Tree
Bottle Top Flowers, Bottle-Bottom Coin Purse, Wallet from Jug, Water Jug Storage Bins, Bottle Lamp, Magazine Rack, Coin Bank, More
CDs
CD Crochet, CD Clocks, CD Spindle Earring Holder
Computers
Computer Case Soda Dispenser, Wallet from Keyboard, Change "Purse" from Computer Mouse, PCB Bracelet, Keyboard Keys Badge, CD Sleeve, Keyboard Name Sign, Keyboard Keys Bracelet, Keyboard Key Thumbtacks, Key Calendar (Try doing keys separately)
Other Plastics
Toothbrush Bracelet, L'oreal Fish (Scroll down), Soda 6-pack Ring Snowflakes, Homemade Shrinky Dinks, Magnetic Rubik's Cube from Dice, Woven-Marker Basket, Card Pocket Wallet, Tic-Tac Ribbon Dispenser, USB Barbie
Ideas: Using flat plastic sides from bottles and jugs as panels, connect to make clothing/cosplay armor, interesting chandeliers, window treatments, a blind for car windows for young children, shingles for a shed/child's playhouse.. etc.