I'm also working on some more revealing clothing for The Sims 3, in some cases absurdly so.

The clothing uses custom meshes based on various standard EA ones but mine are on the primitive side. Same thing for the textures. For example, there are no normal maps, and little shading on the skin where cloth edges lie against it.

Some snaps of the current work in progress:

A bolero jacket, some cords that are unzipped & open, and a (very) mini-dress without the infamous flat disk underneath.

            

A western-style blouse, a (very) mini-skirt without the infamous flat disk underneath, a turtle neck sweater that's been hiked up, and another (absurdly) mini-skirt. If you know The Sims, you'll probably recognize some of the standard meshes I used as a basis.

            

When they say every girl needs a basic black dress in her wardrobe, I don't think this is what they had in mind. There's some major ugliness going on with the shoulder straps and it looks worse when the sim moves.

            

A green belted variation on the pink (not-so) cover-up above, plus a blazer for the woman looking to impress at the office. Yeah right.

            

These items can also be used by teens when playing with Twallan's Master Controller mod and using the option to enable adult meshes for teens. Basically I play teens as shorter young adults.

No, you can't download these yet, I'll still working on them.

Because the clothing reveals much of the sim's body underneath, there are sometimes issues with clipping in certain positions, e.g. while sitting. Tinkering with the bone weighting of vertices should help with that I think, along with tweaking the mesh itself, but the game was never really designed to handle this sort of thing.

At least it's fun to experiment with!