Concept 3D is now available as freeware.
It’s a 3D graphics package, written by the late Robert Fingerle and published by US software house Tesseract Software.
Prior to his death, the author gave permission for the software to be freely released for the QL.
The software is configured for microdrive, so you may need to use a FLP_USE “MDV” command to run it from floppy disk, for example. Unfortunately, I have no manual for the software, so I have included a magazine review from 1986 with the software in the form of a Quill _doc file called concpt3d_doc which you may wish to read before trying the software. Alternatively, read the article as a (256K) PDF file on the same page. Although I haven’t had time yet to try running the software myself, the review seems to imply it’s a great 3D graphics program.
The software is available to download from my website at http://www.dilwyn.me.uk/graphics/index.html
I am grateful to Timothy Swenson for obtaining the permission to release the software, and to Rich Mellor for preserving a copy of the software before it was allowed to vanish forever.
Update: Shortly after I wrote this, I was given a copy of Concept 3D patched to run from disk, now available on the same page. Hopefully if we can find a manual and scan it, we can also make that available.