Crafting: ideas of shops, groups, workshops....

Well, if you are including commercial activities then take a look at the Schleiper Shop (the one near Place Jourdan is good) at rue de l'Etang 63, B-1040 and pick up a brochure. Tel 02 588 00 91

http://www.becreativebyschleiper.com/youdo.html

Among many other creative courses (jewellery, painting, sewing, sculpture etc) they do a course called 'Ateliers de Tricot et Crochet' for children (they also do courses for adults) although as this info is over a year old, it would be best to verify

You can often glean information about sewing classes from notices posted in fabric shops such as Tissu Joyce and Chien Vert

Also, a quick google throws up:

this http://www.creacouture.be/sewing-classes-brussels/

and

http://recreart.canalblog.com/

Some info on this subject contained in previous xpat q & as too as I recall!

Crea corner definitely do some courses never been. I believe Jean Rigoux in Overijse used to do painting course but you'd need to contact the store in Overijse to confirm.
Also the awc do some course on quilting etc. so I imagine do other women's clubs and some people take private art lessons with various teachers