I'm working on a (somewhat huge) commission right now, and one necessity to do things right is a small sculpted item. It, however, has to be smaller than the .01x.01x.01 you can get to with just uploading a normal sculpty. Prim torture doesn't work for the workaround for sculpts, the texture itself has be altered to get things smaller.
Considering I'm primarily obsessed with jewelry now, this is a wall I would be running into regardless eventually. I've been avoiding sculpties because they tend towards massive lumpiness, as well as criminal inefficiency in most cases (all the vertices need to be interpolated, and we're talking way more than on a regular prim, and it makes quite a lot of sense that some people are sitting there chugging away with spheres where sculpties should be while they load the things that could have been done in 2 regular prims, which would have loaded far faster and easier). A big part of the problem is we're talking about giving shiny toys to people who don't understand the real practicality behind them (at the Jewelry Exposition, someone was fighting about the exclusion of sculpties in our builds, because "they're the great new thing! She's an idiot to not let us use them! We can just give one of our texture allowances to them!" not realizing that it works on a substantially different principle, and does add more to lag. Also there was a bit of "why can't I do _that_, it just adds to client side lag?" while ignoring the fact that client or server side, LAG IS LAG when it comes to the people who are trying to actually look around. But, I digress). Another big part of the problem is that the system already has serious constraints without adding yet another big imposition on it. Sculpties are marvelous and fabulous and let us do things we couldn't before...and technologically we're not really ready for them, except in ideal conditions. Add in the people who are using them entirely to cheat their prim limits on their sims...and yeah. It isn't a system breaker, but it certainly does mean things run less smoothly than they could.
But yeah, off the soapbox, and back to useful things. Johanna Hyacinth was the only reference I could find to anyone even suggesting cheating the size limit on sculpties. However, I needed to do some trial and error to figure out how to cut the channels- this is how it's done in Photoshop:
Open your sculpt texture.
Open Levels. Move Output Levels more towards the middle, in this case, I chose 60, 195. The more towards the middle you go, the smaller your sculpt (also, as she points out, the more detail that gets lost! So don't go too far! And really, you can't actually make things out well once they're too small anyway), but this ought to be sufficient for my needs.
Save, import, voila! An (almost) identical sculpted item, at a smaller size!
Of rather useful note: the UV mapping will be the same as if it were at the larger size- it doesn't do the thing with inner hollows and the percentage texture thing (Robin Sojourner has a great tutorial book in world on figuring all that out, close to the place to pick up her avatar uv maps).
(Yes, this is extremely basic, but I'm good at forgetting what I've done, and then being stupid trying to figure it out and ignoring the obvious.)