Create a DAX Expression Builder

DAX is very powerful but hard for people to learn. It seems like the pieces are there (Filter panel experience, Calculation Groups, etc.) to build a DAX Expression Builder that would allow new users to create more complex DAX expressions easily. Such a builder would include:
- Choose expression type (measure, column, or table)
- Add one or more variables, each with their own expression
- For each variable:
o Provide the column and aggregation, or desired measure expression to be performed
o Column/Table picker to remove filters
o Column picker for filters to replace with options to choose specific values in that column or choose a relative option (e.g., TOPN), similar to the Filter Panel options
o Column picker for filters to add with options to choose specific values in that column or choose a relative option (e.g., TOPN), similar to the Filter Panel options
o Option to use other defined table variables as filters too
- Enter a Return expression (pick a column and aggregation, or define a more advanced expression using any scalar variables defined above)

If I was a programmer, I would try to make an External Tool that does this. It seems possible.