One of the smaller scale magical items that can be found in my game world are the “Communication Crystals” or “Communication Globes” that facilitate speedy dialogue across great distances. While there are more powerful versions of these that might show up in nerd fiction or in the game here is how to manufacture the simplest forms of these for use by the players.
The first thing that the players must have on hand is a sphere made of raw materials of at least 100gp in value. It can be some sort of metal, glass, crystal, or even just a large smooth semi-precious rock polished within an inch of its existence. Whatever it is made of it needs to be spherical. No reason is given for this, it just looks cool and makes the players have to jump through a hoop.
The second stage is the standard for every magical item creation process, and that is to cast Enchant an Item on the globe they want to become the communication orb. The time for this is not varied in any way so this isn’t something that can be belted out before lunch on a Tuesday. Careful planning and a pristine environment free of any other magical items is necessary to make sure this works. The item being enchanted must make a saving throw vs. spell (Using the same chance for success as that of the caster) in order to be deemed worthy of being enchanted. Note that this will not be known until after the Enchant an Item spell is complete.
The third stage is to cast the following spells on to the globe: Comprehend Languages, Alarm, and Sending. The order in which they are cast isn’t important unless the Game Master wants to be a jerk. This portion of the process is the quickest, but unless done carefully and making sure that no other magical items are present to jeopardize the magicks being woven the entire thing might fail.
The final part of the construction is for the enchanter to cast Permanency on the globe. The object is now ready for use and given the importance of this item it should be handled and used with extreme caution.
Communication crystals can only be used by somebody that has some measure of psionic or spellcasting ability. While using the orb does not take any magic to actually do there is still a component of the device that requires magical energy to activate and utilize. This means that warriors and most rogues cannot on their own use these items, but mages, priests, and bards of at least 2nd level can. They can also be used by paladins that are at least 9th level and rangers that are of at least 8th level. Slothjemian squires are also able to use these due to their basic understanding of magic and ability to use cantrips. In order to contact a specific person via a communication globe that they possess the two crystals must at some point have been intentionally touched together in order to bind them to one another. A communication orb cannot be used to communicate with any entity that does not also possess a similar device and to which it is not bonded. One cannot take a communication orb and start yammering away at it trying to get in touch with somebody. The operator must concentrate on the person they are trying to contact and speak their name clearly in order to activate the signal alarm on the other end. If answered the two parties can then communicate freely for as much time as they wish. For every turn that passes after the first there is a cumulative 10% chance that one or another of the orbs’ magic will overheat and shut down until they cool off. It takes one hour for the magic to regather and allow the orb to function again. This is not a physical overheating but a mystic one so plunging the device into ice water won’t help (but it might cause the sphere to physically contract and shatter, rendering it useless).
Getting control over somebody else’s communication globe can be useful for certain purposes, but remember that you might not be aware who all is linked to it. You may have an idea who is on the other end of a conversation if they initiate it. However you still can’t identify their location, precise identity, or even appearance. Nor would you have any idea who else might be linked and reaching out into the void using divining spells and a communication orb is almost always going to result in something terrible happening.