All of this information is also available in the write up of my Noble Tac Officer's costume, but this a condensed and Worbla-only oriented tutorial to everyone who ever wanted to know how to make it's surface super smooth. Absolutely smooth, to be exact, without any indication to an original surface or any imperfections that lack of skill (my case) may do to your piece. I will also cover pattern making and general construction of Worbla, however, Kamui Cosplay has an amazing book about that, I suggest it for every beginner and even advanced user, it pretty much explains everything besides the "magical" surface.
1. In order to create some unconventional patterns for my shoulder piece I have used Cobracast (got it from www.mycostumes.de) to copy the form of my own shoulder, it literally took me no more than 15 minutes, I have used ~10cm strips, heated those up one by one and placed them on my shoulder.
2. Looking at the reference I have sculpted my shoulder piece from a soft plasticine (cheap, reusable, and pretty easy to work with, no special tools required, I used my fingers and a single blade from a utility knife).
It took me around 4 hours to complete.
3. Using painters/masking tape, I covered the entire piece with it, marked all the edges/connection spots, peeled it off, and cut it to small patterns, two patterns for each shoulder piece part. It is important to glue it onto paper or the same masking tape, so you have them not sticky and holding the curved form, do not flatten those or they shall not work as patterns! :)
Above are all the pieces for one shoulder piece.
5. Make Worbla sandwiches (how to do it you can read in a book by Kamui Cosplay) and press them at the edges, just following the pattern, the patterns will just fall together due to the curve! :)
6. And now - the magic! Even though the raw Worbla creation looks pretty neat, everyone knows that it needs some kind of surface work, be it gesso, wood glue, or my favorite spray filler. In case you need the surface that looks spotless and without any texture, this is the way to go.
a) spray it with spray filler or primer
b) be shocked by all the imperfections revealed
c) put on regular filler for indoor work (just the stuff carpenters use, nothing fancy is needed)
d) wait for it to dry and sand it carefully
e) be amazed by how perfect it's starting to look. To ruin that impression - spray it with spray filler or primer again :D
f) repeat c), d), a), untill there is no more b).
7. It is very relative as to how many coats of filler and primer you may need: it depends on what your expectations are for the smoothness, how messy was your original work, how well do you sand, etc etc..:) I needed 8 rounds of sanding for this one, but only first 3-4 rounds are significant, the rest it, what I like to all it.. licking :))
8. Primer/Spray filler being the last coat, your surface is ready to take in any paint! Very gentle sanding (1000 grit for example) before painting so paint sticks better.
I get my Worbla and Cobracast from www.mycostumes.de
List of all suppliers:
Book about cosplay armor making by Kamui Cosplay: http://www.storenvy.com/products/3889360-ebook-pdf-the-book-of-armor-making