Some figures e.g. most of the DAZ figures include a "Blank" or "Developer" version that is intended for this purpose, basically model your clothing item around a figure in zero pose, zero scaling, zero translations and import into Poser, go to the Setup room,  and load the figure from the Figures library while in the Setup room - this loads just the bones and parameters.  Often it isn't entirely useful to do that, since many figures depend on Joint Controlled Morphs (JCM) to pose correctly, so the rig will require a lot of adjustment and preferably you'd duplicate the JCMs in your conforming clothing piece in some way (don't ask me about this, I'm stumped about that right now).

You can also look into Phil Cooke's Wardrobe Wizard (www.philc.net) and other similar tools like DAZ Clothes Converter, or Crossdresser (www.evilinnocence.com)

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