NeoLemmix Flexi Toolkit
Flexi Toolkit is a tool which helps you take NeoLemmix levels and other content you've made, and put them together into an NXP file which can be run by the NeoLemmix Engine. You can include more than just custom levels - you can have custom menu graphics, custom music, even custom lemming sprites.
Lastest stable version (Old Format): V10.13.15-B
Latest experimental version (New Format): V1.2
To download older versions of the Flexi Toolkit, visit the download page.
For help on how to use the Flexi Toolkit, stop by the Lemmings Forums.