this is an easy "pattern" ya can use for any size...
all ya need:
glue-gun,
bits of wood,
foam/Styrofoam,
paint,
sewingpins,
fabric
saw
now either do as me or just get 4 simple rectangles of plywood or any thin wood.

1: the big part of wood will be the seat...then base the measurement of the other 3 parts on its sides and back..

2: glue them together with a glue-gun.
I use an low heat one so i can push the glue faster into its right places... without burning my fingers.

3: add whatever sort of molding you want on it..

4: I've added a "storage room" to mine..but the sofa stands easy without it too..

5: then add armrests, make them slightly longer than planned so you can cut them into the right shape.

6: a 2nd layer of wood on the seat..it's not mandatory..but gives it a more realistic feeling.

7: paint it the colour you want.
[COLOR="#FF0000"]Cushion!
do not glue it together on the sofa and do not glue it to the sofa!!!!![/COLOR]

1: make a foam "cushion" for the seat and sides. it needs to fit quite snug to look it's best.
I've fastened the cushion bits together with a glue-gun.
[COLOR="#FF0000"]do not fasten the cushion to the sofa!!!![/COLOR]

2: make the back cushion and fasten it to the rest of the cushion..also with a glue-gun.
I've made a low back cushion..but ya can make it any size ya want.
[COLOR="#FF0000"]do not fasten the cushion to the sofa!!!![/COLOR]

3: cut out the fabric you have chosen for the cushion and fasten it with sewing pins to the foam.
then fasten it to the foam, i used the glue-gun..but you can probably sew it also.

4: when the sofa is dry..add the cushion.
since its not fastened to the sofa..its easy to change when one grows bored with the fabric..
Hope this has been helpful..
