Anduraga recently posted an excellent guide to creating a custom mountain placeable for use as a background element in a module on his blog. Here's a quick teaser:
We'll be creating a two-dimensional backdrop of a mountain for NWN2. This placeable will be no different than the Tree Cards in the toolset. Throughout this tutorial, I will be saying Photoshop and Max. If you're using a different program, then Once you have those programs (Photoshop and Max installed), we can finally begin making our textures.
Read the full post here:
It's a long post but a great read if you are interested in exploring custom placeables or need a specific placeable like this. Thanks Andurag!