Let's get something straight from the beginning, I love gnomes. My first ever AD&D (1st Edition) character was a gnome. So don't get the idea that I hate gnomes just because I created a table about their strange tinker machines going crazy. I do have an ulterior motive for it, but more on that later. First, let's discuss tinkering.
According to the PHB (p. 37), a tinker gnome can spend 1 hour and 10 gold to construct a Tiny clockwork device with AC5 and 1 hp. Three examples are given of devices that simply work; there are no errors or glitches with them. This led me to wonder what happens when a tinker gnome spends 100 hours and 10,000 gold. That led me to the thoughts that created the table below. As much as I personally like tinker gnomes, I DO NOT think they are good inventors. My reasoning for thinking that gnomes are NOT good inventors is this: if gnomes WERE good inventors, then D&D would be a SciFi game. Since D&D is "about storytelling in worlds of swords and sorcery.", then it is NOT a SciFi game. Thus, I postulate that gnomes are NOT going to revolutionize the worlds with their fantastic and wonderful contraptions, but that doesn't mean that they shouldn't try, right? Go BIG or go home, right? That is why I created the table below.
Here's the part where I say that this table is NOT meant to be the best and most complete strange gnome invention malfunction table that you will ever see. In fact, I know that gnomes are an optional race in 5e and that many DM's don't allow them at all. Some people hate gnomes. Some hate tinkers and some just hate both of them for good measure. So I know that every DM must decide for their own worlds if tinkers even exist, if they can craft larger items, and what happens when they do. I don't intend to try to answer these questions for you. I just want to get you thinking. OK, it's table time. Here's 20 Things That Could Go Wrong with a Tinker Gnome's Invention. Happy Gaming!
A belt has snapped - What did it connect to? Was it a drive belt? Was it large or small? Was it a seatbelt? Was it the belt holding up the inventor's pants?
A magical smoke escapes from the device - Roll 1d4 1 - Everyone in the affected area is dyed some random color, 2 - All who come into contact with the smoke laugh uncontrollably for 1d3 rounds, 3 - The smoke affects all who come in contact with it by giving them minor hallucinations, 4 - The smoke affects those who come in contact with it by increasing the individual's greatest trait. Sad people become suicidal; angry people become homicidal, etc.
Runaway clockwork - How big is the clockwork and what does it power? Is there more than one clockwork on the device? Is there a massive power surge when the clockwork accelerates out of control? Does the clockwork slow back down? Shake itself apart? Explode?
Loud sound during main function - A loud, repetitive sound occurs anytime the device is used. Does it prevent communication? Does it hinder the function of the device? Does it annoy everyone that lives within 2 blocks of it?
The device speeds up - How fast does the device speed up and what happens when it does? Does it slow back down on its own or does it need help to do so?
There is a fluid leak - What kind of fluid is it? Is it magical? Is it water, oil, fuel? Is it flammable? What happens to the device now that it is missing the fluid?
Is it coming apart? - The device is shuddering and shaking badly. Are pieces falling off it? Does the device still have its structural integrity?
Clockwork freezes up - How big is the clockwork and what does it power? Is there more than one? Is there a massive power failure when the clockwork freezes up? Does the clockwork start back up or do something else?
Vibration, rattle, or shake - A terrible vibration, rattle, or shake will develop in the device that seems to threaten to destroy the device, but really just makes it make more noise.
The device slows down - How quickly does the device slow down and what happens when it does? Will it speed back up on its own or does it need help to do so?
A bent gear - A bent gear causes a clockwork section of the device to jam up. How big is the gear? Can it be replaced while the device is running? Can the clockwork be unjammed or will the device as a whole seize up?
The device catches fire - How big is the fire? Is the fire natural or magical? Does the device use fuel and if so, how flammable is it? Does the device have crew members? Are they harmed by the fire?
A worn out cog - A worn out cog falls from the machine during a wild shaking episode that stops as quickly as it started. Was the cog necessary? If so, what did it do and how is the machine acting differently without it?
A dangerous smoke escapes from the device - How is the smoke dangerous? Is it poisonous, magical, or something else? How far does it spread? How does it affect people who come into contact with it? Does it affect animals differently? What about plants?
The device suddenly begins spinning like a top - On which axis is the device spinning? Is it spinning left or right? Is it spinning fast or slow? Does the device have crew members? Do their seat belts work?
The controls break - How broken? A little bit broken or a LOT broken? Can the controls be fixed? Can the device be turned off some other way? Is there another way to control the device besides the main controls?
Random strange noises - The device begins making random weird and unexpected noises. What kind of noises are they? Do the noises sound like anything familiar? Do the noises affect the operation of the device or the operators of the device?
The device suddenly - 1) Shoots 10 magic missiles at random targets within range, 2) Disappears for 1d3 rounds and then reappears, 3) Everyone within 60 feet of the device must shout instead of talking normally for 1d4 rounds. 4) The area in a 20 foot radius around the device will sprout with 99 wildflowers which last for 1d4 rounds before fading away. 5) Anyone within 5 feet of the device will begin to glow a faint green. This effect remains for 1d3 hours. 6) Polymorphs 1d8 nearby people who were watching the device function into song birds for 1d10 minutes.
The device completely freezes up and stops working for 2 seconds, then it works flawlessly for the next 3 minutes.
Pick multiple problems from above and then finally the contraption explodes doing a d6 of damage for each hour worth of work put into it. If more than 500 hours have been put into making the device, then you can pretty much scratch that town off the map.
Remember when I said that I had an ulterior motive for creating this table? Any of you who have already purchased Pawnbrokers (Thank you for your support.) probably already know why I made this table. Glindenbazz Cogspanner is a tinker gnome who both owns a pawn shop and creates fabulous gnomish inventions. He needs people to test his inventions and your PC's would be ideal test subjects. You can learn more about Glindenbazz on page 7 of Pawnbrokers.