MNblockhead
A Title Much Cooler Than Anything on the Old Site
My first 5e campaign was an open world sandbox campaign. I did most of the broad strokes world building myself, because that was a large part of my enjoyment with the hobby at the time. The third-party material I would use were mostly adventures that I thought I could plug in a pinch and ways to quickly pick or generate settlements, NPCs, encounters, etc. Basically, to fill things in. What I list below are only what comes top of mind from memory, I use a lot more, but would need to go back and skim over my materials for that campaign in Google Drive and the Foundry world I created from the material I exported from RealmWorks.
I was an in-person game, so I could go into different approaches and products I had for battlemaps, minis, terrain, and other physical assets for a sandbox campaign, but I'll just focus on print/PDF material for now.
First, I found ENWorld to be a great resource and was a Patreon member for years. I didn't use everything, but there was enough that I did use to make the sub well worth it. ENWorld has since published a number of collections of locations, adventures, etc., so it is easier to just buy what you need if you don't want to subscribe.
Kobold press's book of lairs gives some nice drop in encounters/mini adventures that are easy to drop into any campaign. There are not many of them, but they span all tiers of play. You do need the Kobold press's Tome of Beasts as well (I think that's the one, their first 5e monster book), but it is an excellent monster book.
At the time I was using Cityographer, software that will generate a map of a village or town and populate every shop and home. You can create or edit the default text files used to randomize it to fit your campaign or specific areas and regions. I could generate a village or small town on the fly. For larger settlements the maps would get a bit wonky and for important locations I would pre-create and edit to get exactly how I wanted it. But for some random village or town the PCs were just passing through, it made it easy and fun. It was actually less work than collecting an curating large number of drop in village/town maps.
DnD Beyond's character generator is good for quickly creating NPCs.
Frog God Game's Quests of Doom series of books (I have 4 of them, don't know if they've published more since), gives a nice variety of small adventures for all tiers.
I used a lot of maps from 0one game. There website has a good collection of detailed maps for entire villages, Dwarven fortresses, etc. Their PDFs have features to layer on and off map elements and they print well.
Necromancer Games: Book of Taverns
Bill Webb's Book of Dirty Tricks
I was an in-person game, so I could go into different approaches and products I had for battlemaps, minis, terrain, and other physical assets for a sandbox campaign, but I'll just focus on print/PDF material for now.
First, I found ENWorld to be a great resource and was a Patreon member for years. I didn't use everything, but there was enough that I did use to make the sub well worth it. ENWorld has since published a number of collections of locations, adventures, etc., so it is easier to just buy what you need if you don't want to subscribe.
Kobold press's book of lairs gives some nice drop in encounters/mini adventures that are easy to drop into any campaign. There are not many of them, but they span all tiers of play. You do need the Kobold press's Tome of Beasts as well (I think that's the one, their first 5e monster book), but it is an excellent monster book.
At the time I was using Cityographer, software that will generate a map of a village or town and populate every shop and home. You can create or edit the default text files used to randomize it to fit your campaign or specific areas and regions. I could generate a village or small town on the fly. For larger settlements the maps would get a bit wonky and for important locations I would pre-create and edit to get exactly how I wanted it. But for some random village or town the PCs were just passing through, it made it easy and fun. It was actually less work than collecting an curating large number of drop in village/town maps.
DnD Beyond's character generator is good for quickly creating NPCs.
Frog God Game's Quests of Doom series of books (I have 4 of them, don't know if they've published more since), gives a nice variety of small adventures for all tiers.
I used a lot of maps from 0one game. There website has a good collection of detailed maps for entire villages, Dwarven fortresses, etc. Their PDFs have features to layer on and off map elements and they print well.
Necromancer Games: Book of Taverns
Bill Webb's Book of Dirty Tricks