Hi Zio Nick,
SkyDemon has the facility to create custom data such as airspace and airfields as well as a variety of other data-points. This feature is only in the PC version (since it is fairly heavily reliant on the precision of mouse-point-and-click) but you can use the cloud storage functionality to transfer this data across to your mobile devices.
Lots of instructors/trainers create these areas for various different purposes, and we use it internally when airspace is not sufficiently well described in our automatic AIP data feed.