Engineers like to tinker. So let them tinker. Then when they bring you whatever it is they've made, first you say you're too busy to meet with them. Then you say you've changed your mind and you will meet with them after all. Then you wait until they're all in the conference room with everything set up, and you send Katie down to tell them that you're going to be a little bit late. You make them wait an hour. Then two hours. Then, at six in the afternoon, you send Katie down to tell them that you've changed your mind again and now you can't make it. Then, finally, you set up another appointment and this time you do meet with them -- but before they can even speak you just look at whatever it is they've made and you say, I'm sorry, that's a piece of shit, and you walk out. Trust me, engineers love this. They're all masochists. That's why they became engineers in the first place.