In terms of equipment, there are: 'Hunting traps'. There are also caltrops. And there is the snare spell which uses some rope. Probably some others I've forgotten or just don't know about.
Are there specific rules somewhere detailing how to handle the creation of other types of traps? I have considered a stealthy character (ranger or rogue scout, possibly) and using traps more prominently in gameplay. If I wanted to create a dart trap, maybe I have a dart, some poison and some tools, and the DM may allow me to make an ability check using those tools to create it - something like that.
Easy enough to homebrew as we have access to loads of information regarding traps in dungeons, but I am wondering if this kind of thing has been addressed in a source book already? I've done some searching but the keywords are very common so I may just not be finding what already exists.
Yes. Xanathar's has rules for using thieves tools to create a trap as part of a short rest. My interpretation of the rules is that this process sets the trap in place - e.g. you can use these rules to dig a pit trap and camouflage it, but you can't use them to make a hunting trap (that would be smith's tools). For some reason, PC-made traps don't appear to allow a save or need to roll to hit - they have enough rules to figure out the perception, investigate, and thieves tools checks necessary to find and disable them, but other than that, they just do damage, with no mechanic given for dodging it.
If you want to house rule that, your rogue arguably has two well-defined save DCs based on the Xanathar's rules: 8+prof bonus+dex (dex also disables traps) and 8+prof bonus+int (int also ties knots; Xanathar's implies, imho, int should very often be used for tool checks). DMG p191 has loose rules for converting a save DC to a roll to hit for traps that roll to hit, like a tripwire-triggered crossbow.
Unfortunately, the only given mechanics are for a damage dealing trap - there are no rules given for, say, making a snare trap out of a rope, or actually digging an actual pit. Here are some rules that may help you persuade your GM:
PC-made traps generally deal static damage - your skillcheck was the damage roll. The DMG has optional rules in it for converting proficiency bonuses to die rolls, which can be applied in reverse to falling damage. If you do this, you can argue a PC-made trap can be a pit, with depth floor(floor(check/2)/3).
On the other hand, if your GM lets you do this, you may then add spikes to the trap, increasing the damage again.
On the gripping hand, you can add poison to a PC-made trap anyway to add damage; spikes in a pit are the same thing but cheaper.
DMG p191/Xanathar's p116 have trap damage by tier for a setback trap and implies setback is the appropriate description for a trap unlikely to kill. Tier easily maps to size category, letting you argue that you can convert 5 points of trap damage to set a snare for Medium and smaller prey, 11 for Large and smaller, 22 for Huge and smaller, and 55 for Gargantuan. Since your actual damage is half your check (rounding down), this probably means you'll only be able to set snares for Large and smaller targets, at max. I'm defining a snare as much like the spell, so a snared target is effectively restrained and grappled by the trap and hoisted in the air to hang prone.
DMG p122 has rules for a weapon trap built from a net, rather than damaging weapon like a dart, blowgun, or crossbow. It seems credible to argue to your GM that your trap deals no damage at all, regardless of check, and instead just nets the target. Different rules for the same trap are in Xanathar's on p114-115, but I think none of the differences matter here (I think the only differences I see are that the Xanathar's one has higher DCs to spot and disable, which aren't relevant to PC traps, and explicitly lets you attach bells to the tripwire, which mostly serves to let you argue that when you make a trap from materials on hand, you should be allowed to include a ringing bell if you have one).
Xanathar's p116 has rules for thinking of traps in terms of spells, which may let you argue in favor of a trap that acts like the Snare spell directly, and/or other spells that can act like traps, like Web , Grease, Magic Mouth, or Alarm.
Xanathar's also has rules for a bear trap, and I think any reasonable GM would let you turn a hunting trap into a bear trap with either proficiency in thieves tools or a thieves tools check against a relatively low DC - it's basically a hunting trap with higher DCs and damage but also it needs to roll to hit instead of inflicting a save, so it won't ignore plate armour like a hunting trap will (I haven't done the math on which is actually better for restraining a bear or anything).
In terms of equipment, there are: 'Hunting traps'. There are also caltrops. And there is the snare spell which uses some rope. Probably some others I've forgotten or just don't know about.
Are there specific rules somewhere detailing how to handle the creation of other types of traps? I have considered a stealthy character (ranger or rogue scout, possibly) and using traps more prominently in gameplay. If I wanted to create a dart trap, maybe I have a dart, some poison and some tools, and the DM may allow me to make an ability check using those tools to create it - something like that.
Easy enough to homebrew as we have access to loads of information regarding traps in dungeons, but I am wondering if this kind of thing has been addressed in a source book already? I've done some searching but the keywords are very common so I may just not be finding what already exists.
Yes. Xanathar's has rules for using thieves tools to create a trap as part of a short rest. My interpretation of the rules is that this process sets the trap in place - e.g. you can use these rules to dig a pit trap and camouflage it, but you can't use them to make a hunting trap (that would be smith's tools). For some reason, PC-made traps don't appear to allow a save or need to roll to hit - they have enough rules to figure out the perception, investigate, and thieves tools checks necessary to find and disable them, but other than that, they just do damage, with no mechanic given for dodging it.
If you want to house rule that, your rogue arguably has two well-defined save DCs based on the Xanathar's rules: 8+prof bonus+dex (dex also disables traps) and 8+prof bonus+int (int also ties knots; Xanathar's implies, imho, int should very often be used for tool checks). DMG p191 has loose rules for converting a save DC to a roll to hit for traps that roll to hit, like a tripwire-triggered crossbow.
Unfortunately, the only given mechanics are for a damage dealing trap - there are no rules given for, say, making a snare trap out of a rope, or actually digging an actual pit. Here are some rules that may help you persuade your GM:
Xanathar's also has rules for a bear trap, and I think any reasonable GM would let you turn a hunting trap into a bear trap with either proficiency in thieves tools or a thieves tools check against a relatively low DC - it's basically a hunting trap with higher DCs and damage but also it needs to roll to hit instead of inflicting a save, so it won't ignore plate armour like a hunting trap will (I haven't done the math on which is actually better for restraining a bear or anything).