Zick-Zack [Alte Heerstraße 16, 41564] is a small but nice shop. Unfortunately there is no fabric shop in Kaarst, so, if you like to sew, you have to go to Ikea or to Neuss (the city near by).
At the Gare du Neuss [Karl-Arnold-Straße 3-5, 41462 Neuss, Germany] in Neuss (which is the city next to Kaarst) there is a Handmade market where crafters can sell their designs!
If you like Italian food, try the il trio Restaurant-Bar [Neusser Straße 1, 41564].
Café Einblick [Alte Heerstraße 16, 41564] is a great place. Disabled people serve you coffee and cake and also sell their art there!
The Volkshochschule (VHS) [Stadtparkinsel - Waagehaus -, Grevenbroich] offers a lot of classes, otherwise people mostly craft at home I would think
To make crafty friends, try the handmade market in Neuss "designerkram" http://weiberkram.org
For a souvenir, how about a "Meine Heimat 41564" T-Shirt? http://meineheimatkaarst.spreadshirt.de/
For inspiration, just jump on your bike and GO! The area around Kaarst is really flat and we have lots of bike paths so just discover Kaarst by bike!