This answer focuses on gear and is build-agnostic
There is a lantern, or a flask.
This thin black liquid is stored in airtight flasks because it evaporates quickly when exposed to air. Its cloying vapors cling to a target, obscuring vision for a short period of time. You can throw a shadowcloy flask as a splash weapon with a range increment of 10 feet. A direct hit means the target treats the ambient light as one category darker than normal, with a creature already in natural darkness treating it as supernatural darkness. This effect lasts for 1 round. A thrown shadowcloy flask has no effect on adjacent creatures or if it misses.
This lantern does not burn oil, but instead burns shadowcloy. When shadowcloy is used as its fuel, this lantern creates a strange, hazy darkness that decreases the light level for 30 feet around it by one step. Unlike when shadowcloy is thrown at a single target, this haze does not decrease natural darkness to supernatural darkness. One flask of shadowcloy fuels a darklight lantern for 1 minute.
Either of these should work in a variety of situations, but if you're looking for magic items, keep reading. And an honorable mention spell.
The big hitter here is Torch of Palelight. Only 250gp a pop.
This torch is made from a dull, gray wood that bears intricate carvings. It burns like a normal torch, but only gives off dim light in a 40-foot radius. In areas of normal light, the torch reduces the light level to dim. The torch has no effect in areas of bright light.
Mantle of the Darkest Night is neat because it lets you throw it. So, if you're in darkness? You can throw the mantle and step to it. If you're not in darkness, you can activate the mantle and step to a nearby darkness. Total defense is a bummer, but still not bad.
Voidlight Lantern is just a fancy version of the darklight lantern that uses shadowcloy. and it's expensive at 30k
Lantern of Dancing Shadows is even MORE expensive at 40k, but seems to be designed for the shadowdancer, as it specifically turns light towards dim light.
Tree Feather Token Creates a tree. Trees create shade. Doesn't specifically say that it causes dim light, but it should work. Talk to your dm.
Dust of Darkness is worth noting, though, I'm not sure if this requires GM buy-in or not. You coat yourself in darkness. That seems like it should work to me, but doesn't directly call out light levels, so your mileage may vary.
This spell is a weird one. Completely unreliable. But it's medium range and has a 25% chance to provide dim light on any given round you need it.
You cause the illumination in the area to seem to flicker erratically, fluctuating between absolute darkness and blinding brightness.
The level of light in the area changes at the start of each creature’s turn, as determined by rolling a percentile die and consulting the following table.
d% Illumination level
1–10 Supernatural darkness
26–50 Dim light
51–90 Normal light
91–00 Bright light