If anybody wishes to construct your own flux capacitor see the page below. Of course you still end up spending over $200 if you want to make it screen accurate, cause the enclosure material used in the movie is expensive.
http://www.bttfparts.com/board/viewtopic.php?t=857
Many action figure companies have approached Universal for license approval, the studio have no problem with it. Problem is getting approval from Michael J. Fox and his people (agents). Those who remember, the BTTF pinball machine didn't have his image likeness either. After the trilogy ended Michael didn't want his face and image used over several merchandise products and thus restricted his likeness since the early 90s itself.
I still love the detail work Diamond Select Toys has put into the BTTF minimates, I have suggested to them since MJF won't give approval, they could roll out Doc Brown and Biff figures for the time being and then probably make Marty figures without the exact likeness of MJF, similar to what McFarlane did with one of their Terminator license when they couldn't get Arnold's likeness approval. Maybe put glasses on the face or something.
In spite of all the inaccuracies it's still a pretty good looking prop replica. My biggest complaint with DST's Flux Capacitor replica is the color, it should be dark grey. After they rolled out the final product image I canceled my pre-order. Months before the item went into production I and few fans sent accurate dimension information to DST and insisted on the right exterior colors as well. I sent them few screen shots and gave suggestions to make it better.
They responded to several of my emails and suggestions, but when the final product was getting released in the market, they informed me they are sticking with the old design i.e the one with all the inaccuracies.
I hope DST release a screen accurate Hoverboard for their next line of BTTF prop replicas.