The Klassik Stiftung Weimar has made me very happy by publishing (producing?) a toolkit based on Goethe's experiments on colour. The last time I got so excited about a new toy was when I was 10 and my grandmother gave me a rather good microscope.
At first glance this box may look like a gimmick but is actually very well produced, designed and commented. It contains a facsimile reprint of Goethe's first proper publication on colour (Beiträge zur Optik, 1791), a very nice booklet on Goethe's involvement with colour theory (written by Gisela Maul), a set of "playing cards" copying the set made and used by Goethe, separate tables to illustrate his experiments and, to top it all, a real prism. I haven't started "playing" properly with the prism and the cards yet, but the booklet alone is worth the price of the box (around £22). Since most of the original drawings and items relating to Goethe's colour studies are in the archives of the Klassik Stiftung Weimar the illustrations are of the highest quality and, luckily for me, come with detailed references and descriptions. I am planning a research trip to Weimar in the near future to look at the originals.
You probably won't find this on Amazon any time soon (despite it having an ISBN 978-3-938753-03-3) but my local bookseller in Germany ordered it for me within a few days.