I have a 12" Blue Extended Star from Rhonda's BOW week #2. I don't know how to figure how many blocks I would need, should I put them together, or should I put a border around each one. I've heard there is a computer program that can show you what it would look like before you do all the cutting and sewing but can't afford it. Does anyone have this program that could give me some suggestions, ideas?

How big do you want this to be?

I was thinking maybe to fit a double bed.

I still use graph paper, a calculator (one can get a decent Texas Instruments one for around $10-$15) and pencil and paper. An eraser and/or white out is also good to have on hand.

A full size mattress top is 54 x 75 inches. Then add how many inches you want it to hang down the sides. Then think about sashings and borders.

I think I would start with 24 blocks - 4 x 6 block layout - that would cover an area of 48 x 72 inches.

Then you could think about whether or not you wanted to add sashings (strips of fabric between the blocks) and that would add some inches.

5 x 6 would cover 60 x 72 inches

5 x 7 would cover 60 x 84 inches

Sometimes what one does is determined by how much fabric one has - and then one improvises if one has to -

One can also draw three or four of the blocks on graph paper, and then copy that and cut and paste.

It is a good thing to see how the secondary pattern will emerge before getting overly committed to something.

Lay some blocks together and see if they look better with or without sashing and then determine the number.
Often a secondary pattern develops that is good for the overall design. My gut feeling is you don't need sashing.