Trajec3D 1.7.1.4 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. Trajec3D.exe is the most frequent filename for this program's installer. The program is included in Photo & Graphics Tools.
The actual developer of the free software is BasRock. We cannot guarantee that the program is safe to download as it will be downloaded from the developer's website. Before launching the program, check it with any free antivirus software. The following versions: 1.7 and 1.6 are the most frequently downloaded ones by the program users.
From the developer:
Trajec3D is a three-dimensional rigid body rock fall analysis program that can simulate the trajectory of volumetric bodies during free fall, bouncing, sliding and rolling. The body shape is selected from a toolbar and the size is a function of the selected geometry, mass and rock density.
You may want to check out more software, such as graphite, Drawing Register Professional or Javelin5, which might be similar to Trajec3D.