This is frustrating as hell especially on Foundary: Perfect alignment of objects. I try two stack to boxes or connect two walls it always appears crooked. Please Help.
Well, what I do is I place the box on top of another as best aligned as I can. After that if you just want to shift it a bit in a direction hover in front of the box (not too far) press "a" until it comes close to being aligned and then press "a" again to drop it. You have to do it very quickly or it'll overshoot. Rotating, you'll just have to match it as best you can.
I do the standard, try for 30 minutes to get perfect aligns, chuck controller at TV in frustration, go buy a new TV from Walmart, and forbid sister from using it... Jk, it doesn't usually take me a long time to align things properly.
Stacking: place base object, then spawn a double box, rotate it so it is vertical, and put it next to the base object. Spawn another vertical double box on another side of the base object. Now you have two "guides" that are perfectly vertical, and right next to the base object. Spawn the top object and place it on the base object next to the double box "guides." Delete the guides. As for alignment, just keep trying. I like to get above it, grab it, and then rotate back and forth very slightly until it comes to rest where I want it.
Listen to the Furious man, he knows much. I do exactly what he's talking about with stacking. It also works with alignment. If you have the first part of your wall set where you want it, spawn a double box and push it up against your wall to where half of the box is on the wall and the other half is in the direction you want your additional walls. All that's left is to spawn your wall and slide it down the side of the box until it meets up with your other wall. Voila! A straight line every time. As for initial alignment, I usually start with a box lined up on the center grate and pushed up against the separating wall, then work my way out from either side with either box-width or stair-width spacing. Good luck; it can be tedious. You might want to take a look at Anderoo's post about wall placement, too.
Put a vertical double box next to the double box that you want to stack on top of. Now you have a vertical guide for straight stacking. Is that clearer? I don't know any other way to say it.
It takes practice, i used to suck at it really bad and i made Asper and Rusty do everything but i am getting better now it just takes a lot of paitence.