You may find a dedicated sweatshirt/tracksuit fabric section in your fabric store of choice. If you don't, just head for the knitwear section and look for a thicker comfortable knit fabric.
As far as fibers go, you can go all cotton, or opt for a poly or acryl cotton blend.
Make sure to pay attention to the inside of the fabric. Sweatshirt fabrics come in loopback and brushed back. If you want that OMG-it-feels-so-soft-on-my-skin feeling, go for brushed.
Du musst keinen Sweatshirt-Stoff verwenden. Andere Optionen sind verfügbar, vom modischen Neopren (aka scuba) bis hin zu einer exzentrischen Wahl wie gebrochener Velour (aka Samt).
