are there any mods out threr that allow manual building,
by this, i mean are there mods that allow building small structures such as forts from "building bricks"
i used a mod once that gave the player several large blocks that could be moved around, combined with decorator assistant it made it quite fun to build a wall
But im wondering are there mods that combine these two functions???

Not that I know of, building with the construction set would be much much easier... that's why it exists.

lol, tcl + building mod = Halo 3 Forge?

anyways, no, I am certain it does not exist because...well we have the Construction set. if you want to "e& build &unquote& something from odd objects that lay around the game, open the cs, open the "container" tab, find the "crate" in the menu, and start building. think of it like...legos!
unfortunately, if you did this, don't think your idea is the most http://www.tesnexus.com/downloads/file.php?id=26692.
anyways, crates don't have havok physics applied, just a collision so you can walk on them without them falling below your feet. Doing this would be more fun anyways.

On a different note, if you had that mod where you can place objects more accurately in game, then in combination with that mod and this mod "THE CAKE IS A LIEEEE!!!!!!!"
which, due to sixual images I cannot give you a link to the download specifically. Just search "Companion Cube" and it will come up. also, please do not destroy vital testing apparatus. and if you do decide to build something with these, http://www.youtube.com/watch?v=Y6ljFaKRTrI.