Border-less Fabric screens (...ones with absolutely NO Trim at all...) are always cool, but the do present a entirely different set of considerations.
- Necessity of very exact image placement / sizing
- Frame must accommodate a French Cleat handing system that allows for a flush fit on the wall.
- Material must be wrapped to the Rear side very neatly, and stapled.
Using standardized Screen cloth requires a frame rigid enough to allow for enough stretching to pull the material taunt without flexing the frame. The best designs employ 1x3 Poplar on "Edge" as the perimeter Frame, and 1x4 Poplar as the Central supports, laid Flat and flush with the rear edge of the Frame.
As far as measurements for the wood goes, the lengths needed are dependent upon the method of framing employed and how the Corners and Central supports will join.
Here is a visual example of a 120"er
A closeup of the "self made" Wood French Cleat
And next below is another simple "Flat Framed" version and a "on Edge" Version where the Central supports are also on edge.
( The next example below is for a much larger Fabric screen, but can serve as a visual example nonetheless. )
The last 2 examples also require that a "Stand Off" be made to keep the material from toughing the Flat outside framing and the central supports. (..it shows Spandex as the Material but of course it can also apply to Mfg Screens)
That's all I can offer without some complete information as to your DIY ability and Tools.
But be advised a good frame will employ the use of a Kreg Jig and Pocket Hole Screws.