All Object placement

Blender Development Fund
Asset Library
Blender Development Fund
Asset Library
GravityDrop Generator
$5

Mars0hod in Addons

Physics Brush
$24

AFX LAB in Addons

Snap Together
$8

Martin R. in Addons

Surface Snap Align — Real-Time Surface Snapping for Blender
$8

Li Shoujing in Addons

Asset Organizer — Grid Layout Tool for Blender
$6.99

Tivan Hajiloo in Addons

Arrangement Tool
$1

shigeru ozawa in Addons

Oh Snap! Dynamic Snap to Mesh Tool
$8 Dev Fund Contributor

Space Robot in Addons