”'It's colored and constructed to hide you in the mist,' Kelsier said. 'And it warns city guards and other Mistborn not to bother you.' He spun, letting the cloak ﬂare dramatically. 'I think it suits me.'—Kelsier
A mistcloak is the cloak worn by Mistborn while traveling through the mists in order to obscure their figure and so prevent them from being seen. It is a hooded garment made from a lightweight material, and consisted of ribbonlike strips of dark gray cloth sewn together at the shoulders and chest. Mistcloaks are constructed to come free when pulled, so that they cannot be used against the wearer in combat.
A mistcloak would be hard to get right. I've seen several people try, and they never quite feel right to me. Maybe they are one of those things that work in my imagination, but might not work in the real world.
What I would be looking for is something enveloping, something grand, yet also much more light-weight than most of the ones that people have made. I know that Vin describes hers as heavy, but that's all relative.
But here's my best answer to your questions:
Colors: All the same shade of dark, charcoal gray. How wide are the strips: Between a half an inch and an inch wide. Material: Cotton, perhaps. Lighter than canvas or wool, for certain. However, I do imagine each tassel being sewn individually, perhaps with a thicker back and an inside that is of something softer and lightweight. Are all the tassels the same length: No, but close. Within an inch or two of one another. Do they drag: No. They're cut so that they obscure the feet, but don't drag. How many layers of tassels: 1 and a half.
The real trick, I think, to making one work would be to, in my opinion, make a cloak which looks cool on its own. Then, slit the bottom 2/3rds up to about the rib-cage area. Sew these into tassels, then sew some more tassels to the inside. Then, perhaps work with the shoulders/inner layers to make the cloak fall down so that it looks enveloping and the sides can fall straight.”—From Brandon Sanderson 
By Mistborn Era 2, the mistcloak has evolved into a mistcoat. Waxillium Ladrian's, in particular, is a long, enveloping garment like a duster with a thick collar and cuffed sleeves, ankle-length and divided into strips from just above the waist.
|Era 1 books||Mistborn: The Final Empire · The Well of Ascension · The Hero of Ages · (Mistborn: Secret History · The Eleventh Metal)|
|Era 2 books||The Alloy of Law · Shadows of Self · The Bands of Mourning · The Lost Metal · (Allomancer Jak and the Pits of Eltania)|
|Shards||Preservation · Ruin · Harmony|
|History||Classical Scadrial · Final Empire · Catacendre · Elendel · Southern Scadrian|
|Magic||Metallic Arts (Allomancy, Feruchemy, Hemalurgy) · Metalborn · Mistborn · Misting · Savant · Ferring · Twinborn · Compounding · Atium · Lerasium · Ettmetal|
|Other Media||Mistborn Adventure Game · Mistborn: Birthright · Mistborn film · Mistborn: House War|