Must have building tools?

I'm curious, does anyone have any tools they feel are "must haves" when building? In my own skybox, I have a number of goodies that lend me a hand while doing builds -- the 10 m floor grid, the prim guide from Dreams, and so forth. But I'm always looking for others.

Mari

A pocket calculator (RL), pen & paper (RL), a texture organizer .. hm, Frans Charming's private building plattform is pretty neat too (and only 100L$). Can't think of anything else right now.

What's a good texture organizer? I'd love to get one that displays textures, like maybe 6 at a time.

Cadroe Murphy's tools for making large circles, spheres etc (or some kind of code like that) are essential if you want to make things that big.

The two things I use all the time though:

Lex Neva's rotate prim while retaining scale script, and some version of Rez Foo/Faux/etc. (in fact some scripts of my own design).

Builder's Eye by Max Case comes in handy especially when you are building big stuff.

Since I prefer building by numbers but suck at math, in-world calculators like Dork-In-A-Box by Makaio Stygian is indispensable.

There are several great texture organisers out.
From what I hear, Toneless Tomba's is the first one and it can handle what a texture organiser is supposed to. My friends and I use the one by Cortex Designs (they also have a free HUD based calculator) whilst some prefer the one by Karsten Rutledge at K.R. Engineering (he also has an affordable particle generator). Both are as good, rich with many advanced features and really easy to use. I would recommend copyable versions at extra cost to easily categorise textures. One organiser can have as many textures you want in but it takes forever to load.
GRAFFIX by phantom Kaos is good with additional fun features but not too practical for hardcore building IMO.

Jeffrey Gomez's mirror prim script. This is invaluable and saves me a ton of time. I use the old one, his newer nerfed one never did work for me.

I wish this was built right into SL itself. Yeah, I know about relative mode but it's a bit annoying to setup. I'd rather just select a plane and say, "Mirror across that on axis blah."

I also use the shift-dupe/ctrl-z trick a lot. Other than the mirror script, I don't rely much upon other's build tools. I do use a grid texture for alignment with larger objects, though. I use the Renderman gridmap.

Oh, and of course, God Mode for the unrestrained camera/select distance. (Which is now in 1.12)

Pencil, paper. ( to sketch it out first!)
a big big big giant ugly box in the sky.
some good music.