Hi Srinath:
Density of ABS, the plastic used for 3D printing, is 1000Kg/m3 (same as water). ABS is one of the best plastics compromise for strength/weight parts (is the one used by LEGO bricks). LEGO manufacture the bricks from ABS powder applying pressure and hot. I don´t know other technologies of plastic molding.
But molds are expensive, and prototipe designs changes until they estabilize. So IMHO is not the right way to start a RTF production. I´d sugest you to start with a 3Dprinted parts until design is considered frozen (same process than software).
I´m still changing small details in my "quad monoblock", there is always place for improvement.
This "quad monoblock" design (see last status in attached figure) will be build by three different persons (Teramax, an australian guy and myself) with same drawings. After this experience I´m sure there will be changes. You are kindly invited to participate in this experience. This could be a good start point for your RTF AQ quad.
For your information, attached are also some pdf files with the 3D part list and the "asembly instructions" (only first pages by now). You can play the 3D model here:
https://grabcad.com/library/multicopter ... 0AFD.3dxmlBest
Angel