Haven't written anything inside Maya for a while but if I recall you can use eval() function. http://help.autodesk.com/cloudhelp/2017/CHS/Maya-Tech-Docs/CommandsPython/eval.html "This function takes a string which contains MEL code and evaluates it using the MEL interpreter. The result is converted into a Python data type…
Easiest way would probably be to use QT designer and link the commands to mel commands. http://www.creativecrash.com/tutorials/using-qt-designer-for-mel-interfaces/page1 http://www.creativecrash.com/tutorials/maya-mel-qt-and-you-interfacing-with-the-qt-designer