Cute ideas for USB drives! They must have been huge hits at xmas.
It was very difficult to figure out how to get the clay off the stick to bake so I didn't melt the memory stick in the oven.
Parts of the USB drive would probably be fine but AtomicJam had thought in another post recently that perhaps heating too high could cause the "components on the PCB (printed circuit board) to expand and fail." As I remember, that turned out not to be true at least on the cheapie he tested, but we ended up having a long discussion about which parts of a USB could probably take the heat of curing polymer clay and which couldn't, and he did a test... you should read at least a few of the posts in that discussion starting here:http://www.craftster.org/forum/index.php?topic=327417.msg3781185#msg3781185
... and the posts upward
of that (which would be later in time) for some other ideas, info, photos.
AtomicJam actually removed the plastic casing from his USB drive though then covered it with clay, and also baked his at only 230 F for 20 min.
I initially tried covering the drive with cling film (plastic wrap in the US I think) but then of course that got stuck to the drive itself. I thought about trying to mould them, but was worried that when I baked around the mould the clay would just never come off the mould.
On about the 3rd go I tried using talcum powder on the memory stick, then crafting around that. It took about 3 more goes for me to realise that I needed to regularly slip off the clay, add more powder
If you want to try more ways to create a "sleeve" and/or just make sure a clay "covering" will release from your form after baking, there are some other ways to use forms and/or sometimes releases that should work much better than plastic wrap (a wrapping of plain paper for one, or ArmorAll, etc, etc.).
You can read more about all those techniques and materials on several pages of my site:releases
(...click on Releases
category at bottom of list)http://www.glassattic.com/polymer/glues-Diluent.htm
(...click on the category near bottom of list called Superglue Solvents, etc
)forms & releases
(...click on Removable Sleeves
near the bottom of the list... and perhaps on Plastics too under the Prescription Bottles, etc.
(...start at the top of the page under Finding and Making Your Own Forms
...mostly that area is referring to using small rocks and oval plastic film cannisters as forms (or making forms to simulate them), but would be relevant to what you're wanting to do toohttp://www.glassattic.com/polymer/vessels.htm
(...click at least on the category called Removable Forms
I also took them out every 5 mins and just slipped the sticks inside briefly to make sure that they stayed the correct shape. Not sure if this was necessary,
That usually wouldn't be necessary because polymer clay doesn't shrink enough to notice and it's still quite pliable when warm. And even when cold, if the clay isn't really thick it will generally still bend enough to stick something rigid into it. If you want a sleeve like that to retain its shape, you can put something oven-safe inside while it bakes though, like the cap as you did, or just a stuffing of tissue, cotton, etc (or use a form with release).
How did you make the caps for the end parts btw... in the same way?