Contrast Pro 1.0 for 3ds max 2013 - 2022
https://mariussilaghi.com/products/contrast-pro
Contrast Pro is a modifier for 3ds Max that enhances the details of 3d models. It allows you to quickly add contrast to whole models or to highlight only some specific areas. Areas with large and small polygons can be set to receive the same amount of contrast with the "Uniform" option.

http://www.scriptspot.com/3ds-max/plugins/radial-symmetry
Radial Symmetry is the first and only 3DS Max modifier which allows you to model radial structures and see the end result.

https://www.cg-source.com/floorgenerator.php
FloorGenerator is a plugin for 3ds Max (2013 to 2018) which generates floor objects consisting of individual boards which can easily be textured using MultiTexture. It's a great tool if you're doing architecture visualization and need to make floors that are NOT going to tile and that you can see up close without any pixilation.
Crea3D - Camera Studio v1.0 for 3ds Max
https://www.turbosquid.com/FullPreview/Index.cfm/ID/1722438
Camera Studio allows you to animate cameras much faster!
You can create an orbit or spiral motion around selected objects with just 1 click and easily manipulate it. There is a number of other motion presets. Add shake to selected cameras when you need.The motion path function allows you to create a seamless motion between several reference cameras.
SiNi Software v1.23 3ds Max 2020 – 2022
https://www.sinisoftware.com/Products
The IgNite toolset includes;
Springboard – daily workflow tools located in one UI, including camera and display settings, MAXScript loader, SiNi configuration settings and much more…
Forensic – inspects your scene for issues and fix them before working on a scene. 5* rated by 3DWorld Magazine. Forensic is also available as a FREE version.
Scribe – spline tools, repair, cleanup, optimise any CAD imported drawing.
Sculpt – mesh tools, repair, cleanup, optimise any 3D, BIM model (Revit, Rhino, Sketchup etc).
Unite – relink and archive projects, including over 45 3rd party file types you may use in your work.
Jumble – random object transforms.
Illumi – HDRI setup wizard (includes professional HDRI files from HDRI-Skies).
AMI – Asset management interface that is being developed to future proof your library, including versioning, LOD, multi-formats and more.
SiNiScript – Build your own MAXScripts adding SiNi tools and functions.
PREFLIGHT – Utility checklist tool to run-through and check-off before exporting to Unreal Studio.
The object plugins include;
SiClone – Parametric modeller that allows you to build simple repetitive assets or complex models, with an easy to use UI.
Disperse – 3D paint and object replace tool.
ProxSi – Universal proxy with round-trip editing and asset lock.
Scatter – Random scattering of objects. (Beta).
TurboTriSmooth 1.03 for 3ds max
https://mariussilaghi.com/products/turbotrismooth
TurboTriSmooth is a modifier for 3ds Max that subdivides triangle meshes while producing smoother results and nicer topology than the standard TurboSmooth.
It can be used on triangulated models, cloth, scans, decimated meshes, fluid simulations, terrain or on any triangle mesh.
It will automatically triangulate the models before subdivision.
TurboSmooth Pro 1.02 for 3ds Max
https://mariussilaghi.com/products/turbosmooth-pro
TurboSmooth Pro is a modifier plugin for 3ds Max which produces nice smooth semi-sharp creases on your models, unlike the ugly creases that the standard TurboSmooth produces. It also give you the ability to have linear UVs which in some cases can help in the texturing pipeline.

V-Ray Next Scene Intelligence delivers faster ray tracing, cleaner sampling and more accurate rendering. That means you work smarter – not harder – by automating steps that used to take up valuable time.
Tension Morpher 1.0 for 3ds max 2008-2022
https://mariussilaghi.com/products/tension-morpher
Tension Morpher is a modifier plugin for 3ds Max that quickly and easily adds realistic stretch and squash effects to parts of animated characters and objects. It also can be used to create wrinkles and preserve the volume on deforming meshes.
Shell Pro 1.0 for 3ds Max 2013-2022
https://mariussilaghi.com/products/shell-pro
Shell Pro is a modifier for 3ds Max that creates a shell around models without causing self-intersections unlike the standard Shell modifier which produces a lot of self-intersections. Surface details are also preserved very well.
Path Deform Pro 1.0.1 for 3ds max 2013-2022
https://mariussilaghi.com/products/path-deform-pro
Path Deform Pro is a modifier for 3ds Max that deforms models along a path without causing self-intersections unlike the standard Path Deform modifier which produces a lot of self-intersections. It produces less pinching/stretching where the path bends.
Deformation Cleaner 1.0 for 3ds Max 2008-2022
https://mariussilaghi.com/products/deformation-cleaner
Deformation Cleaner is a modifier for 3ds Max that smooths arbitrary deformations of a model without smoothing the original detail. It can be used as a fast post correction step on top of any deformation.
Clothify Pro 1.02 for 3ds max 2013-2022
https://mariussilaghi.com/products/clothify-pro
Clothify Pro is a modifier for 3ds Max that makes modeling and animating cloth easy, controllable, artist-friendly, fast and non-destructive. You get instant results, no waiting around for a simulation to finish. Painful sculpting of cloth can also be avoided.

Advanced UV Normalizer (AUVN) is a tool for normalizing the Texel Density across different objects.

http://www.scriptspot.com/3ds-max/scripts/polysmoother
It allows you to visualize and manage the Smoothing Groups in a quick and easy way. You can set Hard and Soft edges, select edges by convexity, copy, paste, modify and optimize Smoothing Groups, as well as convert them from and to UV mapping, among many other features.

PolyUnwrapper is a complete set of professional tools designed for the texture artists, especially for the architectural and game industries.

http://www.scriptspot.com/3ds-max/scripts/xformer
XFormer is a tool that will allow you recover the transformation of an object.

FROST is a superfast particle mesher which can generate a single mesh from particles, vertex clouds, object positions and point data files using various iso-surface and geometry cloning techniques.

An easy to use Particle Simulator for 3ds Max designed to simplify and accelerate the creation of high volume particle clouds driven by Velocity Fields (originally available as Stoke MX 1.0). Supported Velocity Field sources include FumeFX simulations and Stoke Velocity Fields, other particle animations fromParticle Flow, Thinking Particles or external particle file sequences in PRT or RealFlow BIN formats, 3ds Max Force SpaceWarps etc.