Simons pages are protected by ordinary copyright, but you are welcome to use models, text and pictures as long as you refer to Simon Andersen or to In particular, you may use (give, teach, diagram, publish) the models as you wish. More formally:

Creative Commons License Origamimodels by Simon Andersen as well as text and pictures (by Simon Andersen and Hans Dybkjær) are licensed under Creative Commons Attribution 2.5 Denmark License.
You are welcome to use all materials for private use, including printing, reuse, folding models and give them to others. In particular, you are welcome to teach others, also as a hired teacher. In other commercial contexts, e.g. books, television or marketing, you may also use then models (but ask if you want to use text or pictures).
This permission does not extend to pages or images or other material marked by other rights and permissions from other people. In these cases explicit permission must be achieved from the respective right owners.

Simon and I will of course be happy to know if you can use anything from these pages, see the contact page.

Please note that this is a more free permission than copyright for in general.
If you have questions, please contact me.