DIY Cardboard Guitar

Ikat bag has instructions for making a guitar out of cardboard, rubber bands and a paper tube.

Good for ages 8 and up.

Get the instructions here:
http://www.ikatbag.com/2012/07/cardboard-guitar.html

Minieco has a box version using rubber bands and split pins.  There aren't any instructions though, just visuals.  There are some helpful tips in the comments though. 

See the images here:
http://www.minieco.co.uk/cardboard-instruments/

Makedo has a more elaborate cardboard guitar and it's shiny.

Get the instructions here:
http://makedo.com.au/inspiration-insight/how-to-make-cardboard-guitar.html

The frakers acres take cereal boxes, popsicle sticks, yarn and wrapping paper tubes for an easier approach 

Get the instructions here:
http://thefrakersacres.blogspot.com/2011/03/happy-its-march.html

Zakka life uses a matchbox and popsicle stick for her version.

Get the instructions here:
http://zakkalife.blogspot.com/2011/06/kid-craft-matchbox-guitar.html

Lyndsxo glamour moms uses a small plastic container to make her cardboard version work.

Get the instructions here:
http://lyndsxo-glamourmoms.blogspot.com/2010/10/daily-play-cardboard-guitar.html

Martha Stewart paints hers orange.

Get the instructions here:
http://www.marthastewart.com/265694/making-music?xsc=eml_crd_2011_08_17&om_rid=NbR$fr&om_mid=_BOS651B8WNdJPT

Free Printable Bus

Il favoloso mondo di carta di toto has really beautiful free printables like the bus above. 

Good for ages 6 and up.

Get the instructions here:
http://ilfavolosomondodicartaditoto.blogspot.co.uk/2012/07/bus.html

DIY Toy Car Garage

Disney's family fun has a cute idea for how to make a car garage using cereal boxes, toilet paper rolls and paint.

Good for ages 5 and up.

Get the instructions here:
http://familyfun.go.com/crafts/crafts-by-material/recyclable-projects/park-and-play-garage-930980/ 

Origami Animals

Martha stewart shares a quick tutorial on how to make many origami animals including a dog, bear and buny with one technique and different folds for the ears. 

Good for ages 11 and up.

Get the instructions here:
http://www.marthastewart.com/269662/origami-finger-puppet-and-flowers

Plastic T-Shirt Bracelets

Mad town macs has a unique idea for how to make a bracelet using markers, t-shirts, plastic bottles and glue.

Good for ages 8 and up.

Get the instructions here:
http://madtownmacs.blogspot.nl/2011/08/plastic-bottle-cuff-bracelets.html

Paper Plate Sun Dial

Easy preschool crafts has an educational craft using a paper plate, straws and markers making a working sundial to help kids learn about time.

Good for ages 6 and up.

Get the instructions here:
http://easypreschoolcraft.blogspot.com/2012/03/easy-sundial-paper-plate-craft.html

Kids Airplane Craft

Parents.com shows how using popsicle sticks, a clothes pin, a little piece of foam, some paint and glue kids can make an airplane.

Good for ages 4 and up.

Get the instructions here:
http://www.parents.com/fun/arts-crafts/kid/simple-wood-crafts/?page=4

Create craft love adds a propeller.

Get the instructions here:
http://www.createcraftlove.com/clothespin-airplanes-party-favors/

Crafts by amanda decorates the wings.

Get the instructions here:
http://craftsbyamanda.com/clothespin-airplanes-snoopy-red-baron/