I made these panties a while ago and I have drawn the pattern for it in the sizes small, medium and large.(Click the images to see them full size.)
hip 88-96 cm / 35-38''
waist 62-70 cm / 24-28''
hip 96-104 cm / 38-41''
waist 70-78 cm / 28-31''
hip 104-112 cm / 41-44''
waist 78-86 cm / 31-34''
Half a meter of 140/150 cm wide (bit more than half a yard of 55/60'' wide) stretch fabric should be plenty for all sizes. You could probably even make 2 or have enough left for a matching bra. The fabric doesn't need vertical stretch as well, but your panties will come out a bit lower over the bum if your fabric only stretches horizontally.
Small piece of jersey crotch lining, 20 cm x 20 cm (8'' x 8'') should be enough. Any cotton with a bit of stretch should do.
About 3 meters of lingerie/picot elastic.
Choosing your size and adjustments
If your fabric is very stretchy and my size chart says you're a bit between small and medium you would probably be fine if you make it in small. If you're just between 2 sizes take the larger size and try the panties on before you add the elastic. If it's too big on your hips, you can easily take it in a little on the sides.
Download the pattern sheets, print them with the settings at full page.
Tape the pattern sheets together. I'm sorry, but this might be difficult, though it should be doable if you just slide the patterns over each other until they match up.
Trace the pattern pieces. You can choose between low rise and high rise, by tracing the A or B line at the top of the back and front. The crotch piece is a separate piece when you make the panties, so trace it separately. Add seam allowances of 0.75 cm (1/3 inch), I find it easier to do this on your traced pattern with stretch fabrics, because they're difficult to mark.
Cut the front and back piece of your panties on the fold. Make sure that you have the stretch direction of your fabric horizontally.
Cut your crotch piece once out of your fashion fabric and once out of your crotch lining.
Pin your fashion crotch piece wrong sides to the front piece.
Pin the lining with the wrong side to the wrong side of the front piece and sew (you may want to baste this first).
Pin and sew the crotch pieces the same way to the back piece.
This way you won't have exposed seams.
Sew the sides of the front and back pieces right sides together with an imitation serger stitch. If you have a serger, use it for these seams.
Now try for size, because not every stretch fabric has the same amount of stretch.
If the panties fit, you can attach the elastic.
Set your machine to a triple zigzag (or a normal zigzag if your machine doesn't have it).
Put your elastic on the right side of the top (where the waist is) of your panties. Make sure the softest side of your elastic is up and the picots are pointed towards the fabric.
Like on this drawing that shows my mad paint skills
Stitch the elastic on as you stretch it a little.
Fold the elastic to the inside and stitch again.
Finish the leg openings the same way.
If the instructions aren't clear, please let me know. English isn't my first language and I'm not always sure how to explain something.