I used a striped cotton pillow ticking I picked up at JoAnns. With a coupon it came to about $3 a yard. It's finer and more tightly woven than regular ticking, and I love the combo of florals and stripes!
You'll need some sort of spring steel hoop boning. There are several kinds, but I tend to use a medium strength variety that consists of two bands of spring steel coated in plastic. You can find it at corsetmaking.com. They have another kind that is similar, only coated in buckram, but I find the plastic stuff is easier to cut and is a little stronger than the buckram stuff. I know that Farthingales has heavier duty spring steel boning, but I've never used it so I can't say much about it. You can figure out how much you'll need by adding together all the circumference measurements you came up with when you drafted your hoops (add an extra 1" for each hoop to allow for overlap). To my displeasure, corsetmaking.com doesn't carry hoop connectors, so I purchased mine in person at Lacis.
I also got my boning cutters ages ago at Laci's for the dirt cheap price of $10. They cut through the plastic coated steel like butter, but may not be as effective on the super heavy duty stuff.
You'll also need enough bone casing or grosgrain ribbon wide enough to act as channels for your hoop boning. To figure out how much casing you'll need, find the width of the fabric in your pattern, then multiply that by the number of bones you're using.
Sew your side seams together so that you have one big tube of fabric. You'll want to flat fell your seam or stitch down your seam allowances so that your hoop boning won't get stuck in that space between the fabric and the seam allowance. Trust me, it's a pain in the butt if you don't.
Once you have your tube of fabric, hem the bottom however you'd like.
Make a casing for a drawstring at the top by folding the fabric over and sewing it down, leaving enough space to run your drawstring through. Just prior to doing this, you can make two button holes at the top center front for your drawstring to pass through, or you can just leave a small gap as you're sewing the casing. In previous projects I've entirely forgotten to do this and ended up ripping small holes in the casing to get the drawstring in. Don't be like me :P
Feed your boning through the channels you made, overlap the ends by 1" and join the together with hoop connectors. I tape mine together first so that the ends stay together while I crimp the hoop connector in place.
I believe it's easiest to start with the top hoop and work your way down. It's also a good idea to put a piece of tape over the cut end of the hoop so that it pushes through the channel easier. Take note- if you failed to flat fell your seam or stitch down the seam allowances as specified in the last step, the hoop WILL get caught and you will get frustrated.
Your fabric will probably be gathered and bunched on the hoops strangely, giving them a misshapen and lumpy appearance. Put your hoop skirt on a mannequin or a willing assistant and adjust the gathers so that they are evenly distributed around the hoops. This takes some fussing, but in the end you'll have a beautiful hoop skirt shaped exactly as you wish! I took my hoops home to wrestle with, but next time I'm going to find a willing victim at TechShop and use them as my mannequin :)
You'll note that I added a ruffle at the bottom of mine. You can easily add one in right after you finish the hemming step.