I made yoga pants and a cute tank top this summer. For the pants I used my pants blueprint and I designed using Pants that Mix 'n' Multiply
For the Tank top I designed it with the electronic e-good located here: https://surefitdesigns.ca/collections/digital-e-goods/products/tank-top-gathered-front
Also, I used a spandex bias tape that is easy and practical to use. Here in Canada you can find it in Fabric Land, unfortunately they sell it by the meter. I am looking for a place that sells it by the roll because I know I will use lots of it.