Re: Where to buy supplies
Rather than unraveling burlap cloth, look for sisal/jute binder twine; it's already in a roll. This material can be bleached or dyed with Rit. Subdued shades are best; so make sure the dyes are diluted.
When working in shaded, wooded zone; shades should be lighter in order to offset the darkening that shadows introduce.
Grays and tans might work for urban camo applications.
Rather than using netting; I suggest sewing (flat finish) buttons onto the garment, then attaching tufts of jute with twine loops that fit tightly over the buttons. That way individual tufts can be easily replaced with different shades for new environments. The buttons won't hang up on projections as easily as netting can.
For snow environments, white poly pro binder twine exhibit a degree of bright translucency that blends better with snow, and the poly pro twine will also accept Rit dyes. Faint gray shades as well a darker colors can be used to build a breakup pattern similar to NATO Winter Camouflage. A very faint blue tint can amplify a brighter, whiter appearance.
Greg