Object Spooner v1.1.5

Use Alexander Blade's ScripthookV plugin in order to use this.

Press F8 while in-game to open. If you select the controller as your input option, you may use the controller (Binds being RB+Down) to use the menu.
Otherwise, use the Num keys to navigate.

Spawn objects, peds, and vehicles, and fiddle with them. You've got 690 slots. Have fun.