I came up with this project because I'd bought a bench with a bench/shoe rack to put by my front door, but felt it needed a bit of padding on top. It also looked a bit plain and could use a bit of color to make it look nicer. I kept it pretty simple, with not a whole lot of measuring and using only basic tools, so it should be easy for even a beginner at sewing to replicate.

Since the bench is where I'm going to be putting on and off outdoor clothing, I expect it will get wet and muddy over time, so I designed it to be easy to remove and clean. Some features that assist in this are that the cushion is tied onto the bench instead of permanently fastened to it, the fabric I chose is washable, and the cushion is actually a big pouch fastened shut with velcro, so the padding can easily be slipped in and out.

Supplies

Materials:

bench (I used an IKEA HEMNES bench)
fabric (any color or style, I chose one that's machine-washable and felt sturdy)
padding (I found pre-cut chair padding at a craft store that was nearly the right size for my bench. You could instead get a larger piece and cut it down to get a more exact fit for your bench)
thread
velcro

Tools:

sewing machine or sewing needles
pins
scissors
ruler

Step 1: Cut and Pin the Main Part of the Fabric

Rather than do a lot of measuring, I opted to make a loose pouch. To do this, I laid the fabric right-side up on my table, put the padding on top of it, and folded the fabric over the padding. I lined it up so that the fabric covered all the padding with a little wiggle room so that the padding could slide in and out later, then cut off the excess fabric. Then I took out the padding and pinned the fabric together.

Step 2: Cut the Fabric for the Ties

With the excess fabric I made four straps to tie the cushion on to the bench. The width of the fabric turned out to be the just the right length for the ties, which made cutting it easy. I measured out strips three inches wide, marking the lines on the wrong (back) side of the fabric, then cut them out. Cutting three-inch strips left room to fold the fabric over to make them stronger and look nicer, plus left room for hemming.

Step 3: Pin the Fabric for the Ties

To hem the fabric, I first folded down the short edges by about a 1/4 inch, pinned them in place, then ironed them so they'd stay flat. Then I folded the long edges down by 1/4 inch each, and also pinned and ironed them flat. With the pins in place, I found it easier to flip the fabric over so I was ironing the side that did not have pins sticking out everywhere, since they kept getting caught on the iron. Once the folds are ironed in place, I took out the pins, folded each strip in half length-wise, then pinned and ironed the fabric one last time.

Step 4: Sewing

Now to put it all together! I started with the ties, using a straight stitch to sew along all the open edges. I made sure to sew over the 1/4 inch of fabric that has been folded down on all sides, in order to help keep it sealed shut.

Next I picked one of the short sides of the big pouch, folded down the fabric all the way around by about 1 inch, an inch, then pinned and ironed it in place. This is the side that will be held shut with velcro, instead of sewn closed. I folded each tie in half width-wise, then pinned two ties to the open side, one in each corner, so that the ties were hanging outside the pouch.

On the other short side of the pouch, I tucked the folded ties inside, lining the fold up to the edge of the pouch, and pinned them in place.

I started sewing with the open side of the pouch. I found unpinning part of the long side made it easier to hem the open end. I started at one end of the open side, then sewed straight across to the other side, sewing the ties down as I went. I opted to use a zig-zag stitch and sew back and forth over the ties a couple times to try and hold them on better. Once the open side it hemmed, I pinned the long side back together.

Next, I hemmed the other two sides of the pouch by sewing through both layers of fabric. I felt there was no need to fold the edges down first, as they'll be inside the pouch so they don't need to look too neat.

Step 5: Turn It Inside Out

Now I just needed to turn the pouch inside out. To keep the corners from getting too bulky, it's helpful to cut some of the fabric off the corners. Just make sure not to cut the thread that's holding it together!

Step 6: Add Velcro and Stuff It

I pinned the velcro to the inside of the open edge of the pouch, hooks on one side and loops on the other, then sewed them in place. Then I just slid the padding in, and the cushion was complete!

Step 7: Tie It on to the Bench and Admire It!

I can just set the cushion on the bench and tie it on, then enjoy the lovely padding and decorative appeal of my new cushion!

I like the cute little bows on the sides, but you could instead make longer ties so the ends trail, or make shorter ties that fasten shut with velcro or buttons.