3D Fractals are a bit of a big white spot on the fractal map. Still I found some websites dealing with this topic.

Paul Nylander 's website at http://www.bugman123.com shows amazing fractal images and a lot of information about that topic. Have a look at his Hypercomplex page - stunning images!  => Ref. [PN]

For discussions about all aspects of fractals visit http://www.fractalforums.org

Eric Baird 's pages at http://www.relativitybook.com are no longer available.

Dirk Meyer's program 'Quat' is not available anymore - maybe a search at https://web.archive.org will help. A great little program that opened my eyes for the beauty of 3D fractals.

2D / 3D L-Systems

L-System was already a subject investigated intensely in the Nineties but I guess for many enthusiasts it never lost its charme. There are quite a lot of websites which let you create your L-System images.

Kevin Roast's 'L-Systems Turtle Graphics Renderer' at http://www.kevs3d.co.uk/dev/lsystems is worth visiting. Instant L-System images!  => Ref. [KR]

Larry Riddle's site at https://larryriddle.agnesscott.org/ifs/ifs.htm has a lot of information about generating IFS and L-System axioms/rules.  => Ref. [LR]

A great tutorial for 2D and 3D L-Systems is available at https://www.houdinikitchen.net/2019/12/21/how-to-create-l-systems/ => Ref. [HK]

Here's another source of wisdom: Steffen Polster at https://mathematikalpha.de/lindenmayer-system-l-system created a program for L-System. Sorry, it's in German. => Ref. [SP]

And here is the knowledge base for all who want to explore/investigate L-Systems: http://algorithmicbotany.org/ - a lot of publications covering all L-System topics by Przemyslaw Prusinkiewicz et al.

Below are the 2 most important publications:

"The Algorithmic Beauty of Plants"

by Przemyslaw Prusinkiewicz and Aristid Lindenmayer => Ref. [P&L]

"Lindenmayer Systems, Fractals, and Plants"

by Przemyslaw Prusinkiewicz and James Hanan => Ref. [P&H]

Generate your 2D Lsystem online at https://onlinetools.com/math/l-system-generator powered by Browserling! => Ref. [BL]

A website they call 'digital Swiss Army knife' as it offers online tools for almost everything.

Visit Robert Dickau's site at https://www.robertdickau.com

A sad remnant of MS DOS Lparser times: Cees van der Mark's site at https://cvdmark.home.xs4all.nl/index.html. Not maintained only some images and a small Lsystem tutorial. => Ref. [CM]

Povray and related websites

This list and the others above are not exhaustive. Here are some links to websites which inspired me or put me on the right track when things went haywire.

Povray - THE raytracing engine available at https://www.povray.org - create your own 3D fractals! Do not forget to have a look at the Povray forums. And special thanks to the guys there for support and for putting me on the right track.

Should you be a rookie here is the Povray website that will make you a master in a couple of month/years :)) and you will love it: Homepage of Andrea and Friedrich Lohmueller at https://www.f-lohmueller.de/index_e.htm - THE compendium for almost everything you need to know about creating Povray scenes

One of my favorite sites in the last 2 or 3 months: Louis Belotto's site .:SCENES:. at http://louisbel.free.fr/scenes/scene000.shtml - there I found what I have been searching for a long time: a 'simple' method to create 3D curves. Well, mostly it's in French but Povray SDL isn't!

An other French site which is worth visiting: Alain Esculier at https://www.aesculier.fr/  - a variety of Povray scene files covering L-System/3D objects and many other things out of the mathematical treasure box

A true source of inspiration and knowledge: Paul Bourke's website at http://paulbourke.net/ - you can spend months browsing his pages and it never gets boring => Ref. [PB]

The Scandinavian Povray Guru: Tor Olav Kristensen's site at http://dataduppedings.no/subcube/index.html - enjoy his Povray images and his amazing photos  => Ref. [TOK]

One of the Povray Gurus of the Netherlands: Ingo Jansen at https://ingoogni.nl/ - his site is minimalistic but his thoughts are as swift as lightning as is his coding  => Ref. [IJ]

Mike Kost's Povray Page at http://povray.tashcorp.net - tutorials, images and more

Tsutomu Higo's site at https://www.asahi-net.or.jp/~nj2t-hg/ilpove.htm - definititely not well maintained but interesting images including the POV scene files

And last not least: Special thanks go to Chris Colefax for his ingenious GALAXY.INC