Open 3D printing communities present many opportunities and promises for innovation and co-creation on the web, broadening participation. However, these communities are also riddled with sensitive content– not safe for work– such as sexual, violent 3D models.
Inspired by the motivation to make online 3D printing community safe and enjoyable by anyone with its open nature, we identify socio-technical challenges in 3D printing communities, primarily investigating Thingiverse, the most popular repository based community. We examine existing 3D models shared for free access and user activities associated with them, and provide insights of:

• 3D printing community users are exposed to many sensitive contents without awareness, but these data consist of rich information (text and images) that could be used to detect sensitivity using existing schemes.
  
• 3D printing specific characteristics make it limited to detect sensitivity using existing data and schemes. Knowledge in 3D printing is required to develop a domain-specific strategy.
  
• There are identifiable opportunities for human intervention in semi-automating sensitivity detection, as the classification model may not always be able to determine the intention behind creative designs and could be limited in reviewing unseen sensitive designs.
  
• With the human-computation technique, we can build and reinforce a comprehensive dataset of sensitive contents, which will offer further opportunity to develop an advanced detection algorithm using 3D features.

Sexual/Suggestive

: things with 3D models of naked human body, full body sculptures or torso with nudity, adult toys, imply sexual activities, and suggestive content.

Violence/Weapon

: contains guns, knives, weapons, and their accessories.

Drug/Smoke

: are accessories and equipment that help consuming drug and models that include drug related content (such as a keychain with marijuana logo on it).

* Red-colored keywords are 3D printing domain specific knowledge or related to community/social platforms.

Sexual & Suggestive	1	nsfw, nude, girl, woman, sexy, female, dildo, sculpture, toy, appreciate, patreon, community, join, penis, adult, sex, check, dick, sextoy, anal, plug, naked, torso, vagina, prostate, bust, art, fun, risk, butt
	2	community patreon, appreciate join, join community, sexy woman, girl nsfw, female girl, nsfw nude, nude sexy, nude sculpture, sex toy, nude female, sexy girl, check design, adult toy, use risk, girl nude, nude nude, female nude, nsfw sexy, vagina woman, nude girl, printable model, support setting, nsfw check, sculpture woman, nsfw penis, female figure, nude art, print support, check regular
Drug & Smoke	1	bong, drug, paraphernalia, pipe, inappropriate, smoke, water, bowl, spam, weed, tobacco, hookah, smoking, ice, amur, fulffy, portable, marijuana, slide, cannabis, chamber, perc, 420, grinder, bubbler, spice, percolated, shisha, kingsized, headshop
	2	drug paraphernalia, bong drug, water pipe, bong bong, paraphernalia inappropriate, inappropriate spam, pipe bong, spam thing, tobacco water, amur fulffy, fantastic amur, fulffy bong, just add, tall water, smoke smoking, metal bowl, skull water, pipe weed, joint holder, bong ice, glass bowl, bottle bong, bong printed, hookah bulb, hold joint, ice catcher, love know, waterpipe weed, pipe smoking, simple hookah
Violence & Weapon	1	knife, karambit, gun, pistol, knuckle, csgo, weapon, cs, prop, 1911, colt, switchblade, blade, brass, throwing, usp, painted, knuckles, survival, strike, ar15, stiletto, knive, butterfly, combat, han, mflb, hunting, flip, sniper
	2	karambit knife, brass knuckle, colt 1911, flip knife, easy print, cool gun, counter strike, karambit cs, hunting knife, knife easy, ar15 lower, cool cool, gun pistol, han solo, print barrel, throwing knife, knife knife, tried printing, pistol video, need glue, dl 44, injury caused, cannon 28mm, laser cannon, combat knife, brass knuckles, liberty m16, csgo flip, 1911 prop, strike csgo

Available here.