I enjoy playing basketball so I created a few technical flats that took some basic inspiration from that culture.  I drew 3 flats - a knit sweater, a pair of pants and a jacket.  

 

Inspiration

 

Technical Flats

I used the gray marker to indicate where there was contrast fabric. 

Rounded Sides Knit Sweater

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Contrast Side Panels Pants

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Double Layer Jersey Jacket

 

Illustration

I also drew an illustration so I could kind of picture how they would go together in a look and to see what colors might work for each garment.