DIY Projects

I'm planning on making two things for my chins as it's cheaper than buying them. A large climbing toy for outside of cage playtime, and a hidey house. I already have KD pine, so does anyone know what to use to attach the wood together? I saw wood glue being mentioned in someone's house construction, is that safe? Is so, could I get a link to a good wood glue?

If anyone has any tips for building chin stuff in general, please let me know.