In 1928 Karl Reinhardt published a first solution to the second part of Hilbert's 18th problem "Über die Zerlegung der euklidischen Räume in kongruente Polytope" in "Sitz. Ber. Preuß. Ak. Wiss. Phys. math. Kl.", p. 150ff, however, it seems that this is not easily accessible on the web. Google claims that it is a 6-page paper. The solution should consist of a 3-dimensional anisohedral polyhedron.
The wikipedia article on anisohedral tilings features only the 2-dimensional polygon from Heinrich Heesch. Similarly John Milnor's article "Hilbert's problem 18: On crystallographic groups, fundamental domains, and on sphere packing" in "Mathematical developments arising from Hilbert problems, part 2" from 1976, explicitly only describes 2-dimensional polygons, including Heesch's polygon, referring to Reinhardt's 3-dimensional polyhedron as
a rather complicated 3-dimensional counter-example
omitting any further details about it.
Question. Where can one find Reinhardt's original paper on the web? How does Reinhardt's polyhedron and the associated tiling look like? Where can one find pictures?
Here is the article
You can also check out this video. It is a YouTube video from a french mathematician (it is in french, sorry) that spent hours looking for this tiling on the internet, without success, to end up ordering an old print of Reinhardt's article from an old German guy, and he found the tiling in the article. You can skip to 12'17 to see it. More tilings are presented at the end of the video, but that are from later articles.