Magic Item Tinkering

Derek Holland
The idea of tinkering or modifying magic items has interested me for a few years now, but the mechanics has eluded me until now. Here are three different ways that you might include the idea in your campaigns. Keep in mind that tinkering requires tools of some sort, not just some mumbling and hand waving. And though I use an hour for the tinkering time (to make it somewhat compatible with 5e), it really is up to the DM in how long it should take.
The first is the simplest. The effect is not altered in the slightest, rather the manifestation and possibly the item's sensory traits (appearance, odor, texture and sound) are changed. Reskinning in other words. A Wand of Fireballs that looks like the typical wand and shoots red flames could be modified so that it appears to be a firearm that shoots fire with the sppearance of white diamonds. Fun, no balance issues and makes encounters more mysterious.
The second gives the items multiple functions but only a few that are accessible at one time. A Staff of the Green could have 20 different plant related spells but the wielder can call upon four of them. Modifying the staff takes an hour and then up to four other effects are now possible while the previous ones are dormant. This could be made more interesting if the DM does not provide all the possible effects of the item, forcing the character to discover them through skill checks or discovery of new tools.
The third has magic items with a few different effects, usually four to six, but each takes its caster level from a pool. For example a Drum of Earth and Stone can cast Dig, Move Earth, Wall of Stone and three other earth related spells selected by the DM. The Drum has a level total of 50 and each must have its own minimum caster level available (so no reducing Move Earth to 0 when not in use). Otherwise the wielder can take an hour to modify the levels in each effect to whatever they desire.
The nice thing about all of these is that they work well in concert, that they some how exclude each other. I don't see any reason that all three can't be used in the same setting or campaign. It all depends on how much complexity you want to provide your players.
Next up, a new kind of monster. I just need to get my hands on a few more resources for research.