I think we're all familiar with the present build model. One thing I've recommended in the past is that once a build has been authorized it should be paid out by a turn by turn MPP allocation in which the player has the ability to abort or delay.
Since we now make the full investment in the initiation phase of the build, why would it not be appropriate for the player to enter the build Q and direct the various productions. Nothing too complicated, just like we right click on the flag entering the Q, now another right click on the build of interest and a pull down menu is activated with the possibilities. Like "Abort" or perhaps "Delay"....how many turns? 1,2,3 etc. and the player recoups the MPP investment for the action(s). Now, once again, observing the build Q, that build suffering the modification displays, "Delay 1 turn" or "Abort" overlayed on the image.
Obviously the "delay" order will go away after the designated turns have been played, but maybe the "abort" order should stand a few turns so that if the player wishes to restart, he could then payback the taken MPPs and restart the project. If a couple of turns go by without action then the "abort" order would signify a complete scrapping of the build and not be available for reinvestment.
One thing that occurs farely often when playing the large scenarios, is that after using all or most of your turn's MPPs, I find, after a thorough last going over of the map, a unit or two, or a research investment or whatever, lacked my planned attention of garnishing some MPPs. Now with the interactive build Q, I have a mechanism to remedy that situation.