We made this bench for the lobby of our business. We knew we needed cushions, but did not have the budget to have a seamstress make them for us. After exploring options, I found some ideas on Pinterest and combined them to create the look you see here. This was very affordable (all three less than $100 total) and easy- it took about 2-3 hours. These are the supplies I used:

A staple gun
Fabric of choice- I used a curtain panel from Ikea that had some stretch.
A board base- I used hard board and peg board because we had it. Thin plywood would work or even heavy cardboard.
Padding- by far the cheapest option was Home Depot 3" thick multipurpose foam.
Scissors
A hot glue gun
A piece of felt large enough to cover the back of your cushion.

Step 1: Prep and Planning

Measure the area for your cushion. Gather your supplies- you may need to order the foam padding from Home Depot, it was not available at our local store. I did this project in two stages, to allow the adhesive to seal the foam padding to the board base. I recommend this if possible.

Step 2: Cut Base Board and Padding

After measuring the area for your cushion, cut your base accordingly. I recommend making your base about a half inch smaller in length and width so your padding will lap over the edge and you will not have any hard edges.

Now cut your foam to be the same size as the area you want to cover with your cushion. It will be slightly larger than your base. I tried several methods to cut the foam. The easiest was to use a sharp knife. I tried scissors and a serrated knife as well, but had the best luck using a sawing motion with a regular knife blade. Be sure when you are cutting to hold your knife straight up and and down and don't cut at a slant. Try to keep the edge you are cutting as smooth as possible as large dips or protrusions will show.

Step 3: Glue Padding to Base

We used an all purpose adhesive applied to the base, then laid the foam over the base. Be careful at this point that your foam is aligned evenly over the board with about a quarter inch of overlap on all sides. I used a flat board and weights overnight to ensure that the foam adheres well to the base.

Step 4: Cut and Attach Fabric

Since my cushions were large, I did this step on the floor. I was using a curtain panel and the width was already close enough. I cut the fabric and stapled over the long portion of the cushion. Before you staple, play with how tight you want to pull the fabric. Too much and you will have tugs in the top edge of your cushion. Not tight enough and your edges will not be crisp enough or have wrinkles.

Now comes the trickiest part- the corners. I folded mine like a present- see photos for clarification. I experimented with some other methods and this worked best for my fabric. Don't make all your folds and staple the end result. Staple as you go- one fold and some staples. Gather excess fabric and staple. Continue until you are finished. There will be some lumps, no worries unless they are really large- trim really large lumps.

Step 5: Add Backing

At this point, the underside of my cushion was none too pretty. We would be occasionally removing the cushions as our bench has storage and we also did not want the staples to scratch the top of our bench. So, I laid my cushions on a piece of black felt and traced with a pencil (the graphite shows on the black) and cut the felt to be about two inches short all around (so the felt is at least an inch from each edge and does not show). Next I used hot glue on about one foot sections of board and laid the felt over the hot glue section by section. Mine was not perfect. I had to occasionally tug the felt to cover staples and a few were left exposed, but over all it gave the cushions a more finished look.

Step 6: Finishing Touches

All that is left to do is flip your cushion over and use your fingers to straighten the edges and create the square look. For the amount of time and money invested, I thought that these looked great!

I hope you enjoyed this Instructable and that your cushions turn out great! Please ask any questions you might have in the comments!