Computing devices for content library projection in computer-based 3D environments are disclosed herein. In one embodiment, a computing device is configured to provide, on a display, a user interface containing a work area having a template of a 3D environment and a gallery containing models of two-dimensional (2D) or 3D content items. The computing device can then detect, via the user interface, a user input selecting the content library to be inserted as an object into the template of the 3D environment. In response to detecting the user input, the computing device can render and surface on the display, graphical representations of the 2D or 3D content items corresponding to the models in the selected content library along a circle having a center spaced apart from a default position of a viewer of the 3D environment by a preset distance.