How to make custom bump maps I'm working on a bathroom interior, and I figured that one of the main things I need is to have a good drywall bump map. I've looked around online to see if there are any good drywall type bumpmaps, but I haven't found anything good/free to use.  Is there anyway that I can create a convincing bump map that looks something like this image (in Cycles):



(Ignore the towel holder). It's okay if it's tile-able, but it needs to be big enough so that it doesn't look repeated.  If a similar effect can be achieved through procedural textures, I'm all for it.
I'm going to assume here that you have a high resolution image of the wall you want to replicate. I'm going to be using this texture from cgtextures.com.

The best way that I know of for this, is to import it into gimp, crop it to a 1:1 aspect ratio:



You then use the make seamless filter to get this result:



Then import it into Blender and use the bump node to generate a normal map.



Please note that this is how I like to setup a material, but the only important parts are the image texture and the bump nodes.