Dr. Stone Wiki
Dr. Stone Wiki

Spartan Crafts Club (スパルタ工作クラブ Suparuta Kōsaku Kurabu) is the twenty-first episode of the Dr. Stone anime.


Making cell phones takes a lot of materials and tools. Senku begins by upgrading their equipment using the waterwheel Chrome and Kaseki invented and built together.

Plot Details

Ginro and Kinro happy they need to do less work.

Having acquired the hydroelectric power plant, Senku decides to make batteries to store the newly created energy. He easily makes a battery using the sulfuric acid and two sheets of lead. Ginro realizes he no longer needs to turn the generator manually and he and Kinro get happy about it. Using the energy and gears, Senku builds an air-blowing machine for iron making, which makes the villagers happy as they no longer need to blow air manually. That gives more time for the villagers to prepare and conserve food for the winter.

Senku's Christmas Tree.

Senku focuses on creating light bulbs. Chrome wonders how will they keep them from burning like the first time and Senku explains that if you want something to burn you add air, and if you don't, you need to remove it. Using mercury, they remove the air of the light bulbs and then seal them. It starts to snow, but Senku wishes to finish the test today. He turns the light on a tree which reminds Gen of the modern world and that today is Christmas.

Gen wakes up Senku.

Having new equipment with lights, Chrome realizes he can go deeper into the caves and obtain new rocks and material. He asks Senku what he needs, but Senku tells him they already have all the materials they need for the phones. Ginro guesses that Chrome just wants to explore and Senku suggests getting more copper as it would be useful. While Chrome goes out, Kaseki asks Senku what is the next thing they will do and Senku tells him its vacuum tubes, which are harder to make compared to light bulbs. They start working on them, but the metal line going through the glass expands from the heat and breaks the glass. Chrome returns with copper and Senku creates copper tubes, which would not expand and break the glass, but then the bamboo filament burnt out instantly.

They continue trying, but fail over and over. Senku states that there is no better material in this age than the bamboo filament and as he can't think of anything else, they are stuck at the moment. Chrome wonders if he got any new rock that may be useful, but they don't find any. Suika does the same and go through the rocks Chrome collected. At night, Gen wakes up Senku telling him its new year and they should observe the sunrise together.

Suika finds a glowing stone.

Everyone gathers on a cliff before the sun rises. The rock Suika carries starts to glow and Senku realizes its scheelite, a gemstone that glows blue when exposed to ultraviolet light. Excited, Senku explains its used in modern filaments, Tungsten. Chrome guesses there must be more further inside the cave. Having only one more set of lights, Senku decides the third member would be Magma as they would need brute force to collect it.



Inventions and Discoveries

  • Level 3 Iron Furnace
  • Lightbulbs
  • Headlamps
  • Copper tube
  • Scheelite

Anime to Manga Differences

Site Navigation

[v  e]
Story Arcs
Prologue Saga
Stone Formula Arc
Chapters 1234
Episodes 12
Vs. Tsukasa Arc
Chapters 56789101112
Episodes 345
Ishigami Village Saga
Kingdom of Science Arc
Chapters 131415161718192021222324252627282930313233
Episodes 5678910111213
Village Games Arc
Chapters 34353637383940
Episodes 131415
Village Origins Arc
Chapters 4142434445
Episodes 1617
Stone Wars Saga
Vs. Hyoga Arc
Chapters 4647484950
Episodes 1819
Communications Arc
Chapters 5152535455565758596061626364656667686970717273747576777879808182
Episodes 20212223242526272829303132333435
Source of the Petrification Saga
Age of Exploration Arc
Chapters 8384858687888990919293949596979899 100
Episodes 35
Treasure Island Arc
Chapters 101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138
The Truth of the Petrification Saga
New America City Arc
Chapters 139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169
South America Arc
Chapters 170171172173174175176177178179180181182183184185186187188189190191192193
New Stone World Arc
Chapters 194195196197198199200
Globetrotting Arc
Chapters 201202203204205206207208209210211212
Stone to Space Saga