Is it Free?
Free-Mo gets its name from the idea of being free to join and free to display your creativity within the standard's framework. Free-Mo standards govern the ends of a module and basic trackwork guidelines. Modules can be single-ended, double-ended, or have multile ends. The guidlines around dimensions of each module allow for connectivity between modules of different owners.
Having your module be compatible with other Free-Mo modules means you follow the standards set forth here.
Ease of Construction
It might seem like a daunting challenge to build a module but it's not difficult. Our blog goes through the process of creation of a module from start to finish.