I continue to share the tools that have accumulated over a decade and a half of work in the industry.

Name: SurfaceDropper — drops objects onto geometry below

Briefly: SurfaceDropper drops selected objects down the Z-axis to the nearest geometry below them, aligning the object to the surface normal at the point of contact. The tool is indispensable for laying out stones, vegetation, props, and any scatter of objects on complex terrain in archviz and game scenes.

Installation:
1. Drag the .ms file into the viewport or select Scripting > Run Script — the script will run immediately.
2. Copy the file to the scripts/startup folder so that the script loads automatically with 3ds Max.
3. Open Customize > Customize User Interface, find the MyTools category, and assign the SurfaceDropper_Drop and SurfaceDropper_ToggleRandomYaw macros to toolbar buttons or hotkeys of your choice.

Functionality:
SurfaceDropper_Drop — main action: each selected object or group is dropped down the Z-axis to the nearest geometry. Raycasting is performed from the bottom point of the bounding box of each object individually, which excludes mutual entanglement of objects from a single selection during mass drop. Objects from the current selection are automatically ignored as potential targets. After landing, the object's Z-axis is aligned to the surface normal at the point of impact.

SurfaceDropper_ToggleRandomYaw — toggles random rotation around the Z-axis during drop (random yaw), without opening the UI. Convenient for quickly alternating modes right in the layout process.

Target surface filter — set through the script UI: a layer or picked set of objects is selected for which dropping is allowed. Objects outside the filter are ignored by raycasting, which is critical in complex archviz scenes where walls, ceilings, and other geometry may be nearby.

Offset — numerical offset along Z applied after landing. Allows raising the object by a specified amount (e.g., +1 mm) above the surface, avoiding z-fighting or partial immersion.

Compatibility: 3ds Max 2016 and above.