There is a cheap and and easy way to make a bean bag of any size and proportion.

Materials & Tools:

bean bag beans or regular beans
spool of sturdy cloth
approx. 3 ft. of Velcro
sewing machine
4-6 in. diameter piece of cardboard tube about 2-3 ft. long
shop-vac (optional)

Step 1: Choose a sofa size to determine amount of materials

Model	Diameter	Length
Pea	3 ft.	3 ft.
Garden slug	3 ft.	8 ft.
Centipede	3 ft.	30 ft.
Earthworm	1.5 ft.	8 ft.
Millipede	3 ft.	1000 ft.

To determine the amount of beans needed, you must first calculate the cubic feet of your bean bag. Bean bags are typically filled to 80%. The equation is pi x radius x radius x length.
The best place to purchase beans is epsmolders.org. The technical term for bean bag beans is “expanded polystyrene beads”. The beans also come in virgin (newly made) or regrind (recycled). There is no reason to purchase the virgin beans, they are expensive and a waste of material, recycle!
Hint: Styrofoam materials are listed under “packaging and shipping materials” in the phone book.

Step 2: Make a plan man!

Cut the material in the size of your decided shape. for example, if you are manufacturing the Pea, cut two circles 3ft. in diameter and three rectangles 3 ft. in length x 3 ft. width. Also cut a 2 ft. square to cover the one foot incision you need to make in one of the rectangles. Cut the slit about 1 ft. from the end.

Step 3: Make your fill hole

Note: a double sided seal reinforced the Velcro closure.
Now, after you have cut your one foot slit about a foot from the end, place Velcro on either side of it. Sew the 2 ft. fabric rectangle onto the the large rectangle piece to cover the slit. Sew only 3 edges! Place Velcro on the other edge.

Step 4: Sew it closed

Remember you are making a tube, so sew the pieces together accordingly (long r rectangle sides match up). Sew the bag inside out so that the seams face inward. Go over them twice for durability. Then sew on the ends in the same manner.

Step 5: Do not spill the beans

It is inevitable that you will be picking beans out of you crack for days to come, so remember to just have fun. Turn the bag right side out and fill using these clever methods:

Shop-vac/leaf blower:

Suck the beans out of their packaging and into the shop-vac
Insert the nosel into your fill hole
Switch the shop vac to “blower” mode

or

Tube fed:

Insert a cardboard tube into the fill hole
Funnel beans into the tube and therefore into the bag

source: Dan, “Bean Bag Sofa/Bed”, www.instructables.com. October 13,2006