I would that my customers put them body measures and the web application create a mannequin/avatar that it wear my clothes or the draw of clothes
For example, the customer choose a sweater and inserts the following measures:
Height = 180 cm
Chest = 104 cm
Waist = 104 cm
Then the web application create a mannequin with previous measures that it wear the sweater choosen (or the draw of sweater). So the customer to see how it can fit on him.