Enabling the .Net framework feature in windows 7 can be done using manually but if you want to do this on all clients ,how do you manage it ? Script Based using OCsetup ? or enabling this feature in Image ? or PowerShell script ?
I go with DISM (Deployment Image Servicing and Management)tool to enable this feature.
Download and install WAIK to get DISM tool http://www.microsoft.com/download/en/details.aspx?id=10333
Deployment Image Servicing and Management (DISM) is a command-line tool used to service Windows® images offline before deployment. You can use it to install, uninstall, configure, and update Windows features, packages, drivers, and international settings. Subsets of the DISM servicing commands are also available for servicing a running operating system
Create a folder with standard naming procedure and place DISM.EXE (for 64 Bit and 32 Bit) ,share folder would be better.
Go to sccm and create new package using the above source location as data Source
Create program with command line : Dism.exe /online /Enable-Feature /FeatureName:NetFx3
Get list of available features from windows 7 machine using DISM tool with command prompt : Dism /online /Get-Features (run the cmd prompt with admin account)
Create Advertisement and move it onto collection you needed.
You know what next to do with this …Monitoring the deployment status and fix the issues 
Thanks brother for a good suggestion, I made it as Application (After setting the alternate location of source files by GPO) to be able to detect it (by Detection Method) and it worked well on many PCs ....SCCM have many ways to do things ....thanks again
Hossam
Systems Engineer
Thanks man for this idea, I'll try it but I have a question:
Can I make one SCCM 2012 SP1 Application like this (DISM tool) for windows 7 and windows 8.1 machines ? I want to deploy Service Manager console on a collection of IT stuff PCs and as you know the .Net Framework is required. And can I give it a Source location in the DISM command? or better set the location by Group Policy: Specify settings for optional component installation and component repair.
Highly appreciated your answer. Thanks 🙂
Create a package in SCCM by copying the windows 8 source files (.SXS folder ..exclude .wim file as it is huge) and try creating batch file to copy the SXS files to the local temp folder on the machine that you want to install and run the DISM command line something like below:
xcopy ".\*.*" "C:\Windows\Temp\" /D /E /C /I /Q /H /R /Y /S
DISM.EXE /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:C:\Windows\Temp\SXS
Haven't tested it though. Give a try.