Ahh yes weathering powders!
I dont have any in my modellers tool kit yet. I must have a look at them and how they work.
One of the good things about scalecast / linka, unlike spending the cost of a kit that will make one model, with linka you can make as many models, and different ones as many times as you like / have enough the moulds for / have the powder for.
They are solid and won't warp. You can make them even stronger with internal walls and floors and the insides are usually MUCH smoother then say any of Hornbys pre-made buildings (not the kits). I bought certain pre-made models only to directly sell them on as the inside walls looked like caves or were plastered by a blind man.
Scenix is the same. All the windows are solid so you cannot see throught them. No good for someone like me who likes to add internal details.
Plus, on a lot of pre-made buildings I've noticed that the windows aren't glued in straight. Useless!
I think the best pre-made buildings I've come across personally (they may be more manufacturers I have not looked at) are Bachmann.
As I started with specific kits that I didn't think I could make and do justice to (signal box, curved roof stores/warehouse) moving up (or down depending on your view) to linka was easy.
No messy glues needed, only pva.
I've even helped young children in my family to make a small house each. Thats how easy linka is.