A modular layout in a rented apartment!

I wanted to build a layout to enjoy with my kids, but we live in a rented apartment with limited space. I started building track boards that bolted together, based on hurnby geometry. This allowed me to get a circuit up and running very quickly, but also over time to add new boards and develop it into a large 4-track roundy-roundy layout with station loops and sidings! A friend was interested in a similar project, so I thought I'd put the information online (especially because I've received so many good answers to my questions from the material on RMWeb!)