Math melts my brain

SL rotations have been quite mysterious to me. Their specific relevance to me is in the fact that they are used as a llSitTarget parameter. In my studying of them (and related topics) I have learned what radians are, and grads, and the relationship between radians, grads, degrees and your garden variety circle. I am beginning even to glimpse why rotations are used in SL instead of just using degrees in a normal vector (I mean, I understand vectors), though I have no idea what gimbal lock is.
My understanding of SL rotations, as given in the LSL wiki is thus: The rotation is composed of four floats. The first three floats can be thought of as a vector, which I guess means that, in essence, they are a vector. So those first three floats describe, in radians, a direction in space. One radian is equal to 180 degrees divided by PI, or 57.296 degrees.
The first trick is to understand what a radian is and how to use it. Then to know that the fourth float describes a rotation around the direction (as an axis?) described by the first three.
These are all the words. I have yet to put them together into a clear mental picture of how a rotation works. Bah! This is all just an invention anyway, to help us understand why the toast always lands jam side down.

Beta grid as a test environment

Obviously, the beta grid was not created to be a free for all, play money upload sim for testing our creations. I believe it was created as a server and viewer test environment.
But it is useful for testing the look and function of textures and sculpts when I don’t have a clear idea what they will do inworld. The upload window sculpt preview is really only useful for verification purposes “Yep, it’s a sculpt alright.”
We are making furniture for Second Life. We’ve made that clear. Unsurprisingly, in the beta grid I have seen names I have recognized from other SL furniture businesses.

Upload fees do add up after a while and the beta grid is a great place for our team to meet and critique design ideas and decide if they warrant further exploration. Granted, by that point the time to create a prototype sculpt has already been spent. But let’s face it, sculpting design ideas and texture creation were already play time for me anyway. There is a breaking point there somewhere that in rl would equate to billable hours, but I don’t know where it is.