This is a model of a structure that I want to cover in fabric. I want to create a pattern to use to cut the material. I tried using unroll and drape but neither was satisfactory (I might not be using the correctly or using the wrong tool altogether. Any suggestions?
shrinkwrap in the WIP maybe 
, but it would go underneath too, so maybe cut the bottom off after. You could probably create a bottom surface for shrinkwrap to use also 
or use grasshopper tools 
There isn’t really enough info in your post to answer the question. Is the structure on the ground or part of something else? Does it fully enclose the structure or just fit over? How closely does it have to fit to the structure? At any rate, there isn’t a magic button for that; You’ll have to model the cover as well and then use Flatten and Squish to turn it all into a pattern. If you provide more info, I might be able to help. I do a lot of design work for products made of fabric.
Cheers.
Thank you for the feedback. The structure is on the ground. The fabric is intended to fit over the structure and be in full contact with the structure.
What’s the scale of the structure? What type of Fabric? I realize that I’m asking a lot of questions but it will inform the way the pattern is made. Most fabric will shorten a bit as it’s sewn unless you have everything set up perfectly during the sewing process and have a really good sewing machine operator. I’m going to make a few assumptions here and say that it is around 8 feet high (2.4ish metres) and the fabric is something like Sunbrella tent or awning fabric. You can start with Offset Surface. The fabric cover will have to be a bit bigger than the structure. If you make it the same size, it will never slide over as there will be too much friction unless you’re using stretch fabric. Then you’ll have to explode, Unroll Developable Surface, Duplicate Border and then add seam allowance using Offset Curve. I’ve attached a file that shows a structure similar to yours, and a cover as well as one of the parts flattened out. Beside that is the border of the flattened part with a 1cm seam allowance added.
Cover.3dm (242.6 KB)
@AlanMattano knows how to do this - but this is not something really suited to Rhino, he uses a different program.
Thx SkyG
Yes, I agree.
I do not understand if he wants to make a simulation or extract and unfold the surface.
@Phil_McCarthy
if you’re aiming to prepare the surface for cutting the actual fabric and it’s a simple surface, you should explode it, extract it, and then rotate it to lay it flat on a plane.
However, if you’re looking to create a simulation, you’ll need significant GPU power (and patience) to simulate the physics. There isn’t software specifically for that purpose, and it’s not achievable with Rhino. Platforms like Clo3d and Marvelous Designer allow for similar operations. The structure would act as a collider. You’d have to cut the fabric, position it, and then stitch it properly. Doing this physically is often simpler than in software.
Thank you for your reply. This is helpful information. I’m not a seamstress by any stretch and the material is velvet. Not a good combination. 
The info you’ve provided will get me welll on my way.
Thank you for your time.
