How to do so /\ read the Upper Question.
There is no possible way to do this using any ROBLOX API if you're asking for a 2D image.
However, I would examine the inventory code used in ROBLOX Battle (Click 'Raw' or 'View Raw' to download.) to see how they did it in 3D. (ROBLOX Battle itself went back to being CopyLocked sadly.)
The script you're going to want to look at is StarterGui.InventoryGui.NewInventoryMain
.