You could get a tiny fan in there just to keep the performance up in hot environments just something to push/pull the ambient heat build up out.

Yes, I agree with you... I will install 2 of them, and would take the place of speakers. One for push & one for pull the air. The speakers will take their place in the front binder. Thanks for the tip heatgap!

Thanks for the comment Eric! I have not finished the description yet and I will add more photos. The idea came from Novena laptop from Bunnie, indeed! But Bunnie is in an other level, made his own hardware, software etc etc... I wand my idea to be more simple, more easy to service, to have more universal parts... (I am building a web site for my projects, more details will come)
The case is two ring binders (folders for store papers), joined together. The green contains the screen and the keyboard-tochpad & the red mainboard, hdd etc...
For the battery issue, I am looking for one of this (http://www.ebay.com/itm/laptop-power-bank-portable-charger-external-battery-30000mAh-universal-5V-19V/161270290378?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222006%26algo%3DSIC.FITP%26ao%3D1%26asc%3D21398%26meid%3D6100989262304821479%26pid%3D100011%26prg%3D9407%26rk%3D1%26rkt%3D10%26sd%3D161222581452). The mainboard (intel dn2800mt) has 2pins for internal power connection & an external power connection, from which I am feeding all the parts... I think that the external laptop battery solution, intergrated inside the laptop, is a good! ( I am sorry for my english... I am not so good...)

What is the case? It looks moderately portable when folded up, but it's hard to tell from the pictures. I wonder if RC batteries would be suitable. It looks like that's what Bunnie is using for his Novena Laptop (https://www.crowdsupply.com/kosagi/novena-open-laptop)

Of course, you'd need some custom electronics to generate the various voltages. Maybe take a look at the picoPSU (http://www.mini-box.com/s.nl/it.A/id.417/.f;jsessionid=ac112). It's an ATX power supply that fits into the connector and runs off 12 VDC.