As Promised, Homworld Gem Technology
Gem technology is a really far-reaching topic, so I'm gonna break it down in to smaller sections. Each section is going to address a kind of technology used for tasks necessary for a society (minus food production/distribution since y'know, gems don't need food). Sections are Communication, Transportation, Energy/Resources, Storage/Housing, Research/Sciences, Construction, and Other.
Canon Communication technologies include the Communication Hub on Earth, which likely could be accessed by multiple gems at a time and could reach at least to Homeworld. It might not still be relevant in modern gem technology, as its rather ancient (thousands of years old), so there may be other, more advanced versions in gem society. A phonebooth-style communication device would be pretty interesting to see! Other technologies include the Diamond Communicator, allowing elite gems to directly contact the diamonds. Its likely the there are more forms of communication, like small walkie talkie type close range devices (maybe for use on missions), and even personal video screens made from something like the fingers of Peridot's limb enhancers.Â
Transportation technology varies a lot in gem society, from ships to transporters. Warships like the green hand ship and the Diamond's arm ships (and leg/body ships depending on your headcanon) seem to be very powerful, often reserved for aristocratic elites or important missions (like destroying the Crystal Gems and checking on the Cluster). Ships seem to vary in size based on the gem's rank and mission, as Aquamarine and Emerald (spoiler?) both have large ships, and the Rubies have a smaller ship (which admittedly has a setting for Diamonds to pilot, but still). The transporter pads are also a very important piece of tech, as they allow for the quick travel between colonies and Homeworld, outpacing even ships that travel faster than light. That being said, ships are most likely used in times of war or unexplored areas (or areas in need of repair). Another theory i have for transportation is that shuttles are relatively common, used in the place of teleporters when they are under repair or just being built. During the Wanted special there were also what looked to be tubes going from building to building, which might be used for objects or even poofed gems.
The gems highly value colonies with resources (though not enough to keep the planet alive lol). For them to acquire these resources, however, they need some sort of collectors, whether that be a highly advanced solar panel, drills for manual mining, or even robonoids that can extract certain materials from matter. There isn't much info on how gems acquire resources, but we know the aftermath of their practices, meaning they're probably not too ecofriendly about it (so don't be afraid to think outside of the box and have some destructive qualities in your machines). I'm also going to include Reproductive technologies in this section, as we know that Kindergartens require lots of resources for the gems to absorb in order to form. The kindergarten drills are a means of injecting the material that later becomes a gem, but there might also be drills to inject non-sentient collectors that migh turn into ship cores or something similar.
Storage and Housing "technologies" are presented in canon (though rarely) as pocket dimensions (like the ones in Lion's mane and Lars' hair) and Kindergarten-esque walls (as seen in the human zoo when we meet the Famethysts). Gems also seem to have pocket dimensions within their gemstone, as they can keep things inside it (like books and gem artifacts). Bubbles are another form of storage, though we don't know if there's a size limit to these (gems seem to be able to make larger bubbles when working together, however, as the whole Cluster was bubbled with the help of its component shards). If gems society was able to figure out how pocket dimesions and bubbles can be created and maintained on a small scale, I'm almost positive they could figure it out on a larger scale, even if it was synthetic in nature (such as a pocket dimension for storing artifacts, like a gem library that doesn't take up physical space). Another little idea i had was how do they store information? Perhaps with non-sentient gems, as they seem to be a recurring design element in the show, and i doubt that a society as efficient as the gems would want something like that for purely aesthetic reasons.
Research, data collection, and science technologies of Homeworld include Plug robonoids (the really big ones that were tasked with examining the progress of the Cluster), Hand robonoids (capable of performing actions much like a sentient gem's hand), Peridot's limb enhancers (put here because she was supplied with information from them, like how one looks something up on a phone), and (i'm assuming) some sort of machine or device to combine gem shards forcibly. There are so many possibilities for this section, so many potential machines and devices Homeworld might have developed that i can't even try to list them.
Construction technologies seen in canon include Peridot's flask robonoids, the ones that squirt out the liquid that fixes the shattered holopads. We don't know what the liquid is or to what extent it can fix, but if Homeworld can develop something to fix their non-sentient-gemmade tech, they might have something similar to heal cracked gems to a certain extent (at least that's my hc, especially since all of the Rose Quartz types are presumably bubbled and can't heal anyone). There might even be construction equipment that lower class gem builders like Bismuth are meant to operate. Like, could you imagine how wicked a hover crane or gravity-defying scaffolding or something would be??
Finally, the last section: Other. In this, I'm including weapons and populace-control devices primarily, such as the Shattering robonoids on Homeworld that seek out renegade gems and shatter them, Limb enhancers (yes i'm listing it here too, because they can be used as weapons), Gem destabilizers, and other devices for controlling or shattering Gems. Something interesting I've noticed about the destabilizers is that so far, we've seen 3 different types: the yellow ones on the Hand warship that disrupt a gem's physical form, the (more flourished) blue ones on Aquamarine's ship that we don't know if it has the same power, and the double-ended destabilizer silhouettes from the sdcc trailer (spoiler?). Because of this, my personal hc is that different colored destabilizers have different powers, possibly correlating to the Diamond whose color matches. In the art book, there is a gem tech page dedicated to the sketches and descriptions the crewniverse made in a brainstorming activity, and while none of them are canon, there are some interesting ideas for fanon devices.
The main tips I would suggest to anyone making fan gem tech is don't be afraid to think outside the box, incorporate canon principles to them for a more canon feel (like making a new kind of robonoid to assist your gem in their job), think of a purpose and make the device efficient at it, and have fun with the design (hovering parts, geometric designs, abstract shapes, seemingly blank exterior, whatever you want basically). There's practically no end to the possibilities, so don't stress about it too much! Especially since there are so many facets (heheh, pun intended) of Gem society and technology that we don't know about!!