Singularities can be found in the end sucking up blocks in their path and are hard to obtain due to how dangerous and unstable they are, while trying to obtain one it will pull items out of your inventory never to be seen again, you will also be given the effect of "Warping" which makes your vision stretched out and your screen shake, if you die to one the death message will say "player has been stretched in incomprehendable ways". This needs to be contained in a singularity box.
if you obtain one successfully, it's only a matter of time until it breaks out of the box and kills you, also returning to its entity state, it can take about 3 minutes for it to break out. You will have to craft another singularity box.
if you get 4 end crystals and 4 glass panes, you can now stacraft the singularity box. This is what the Cosmite armor and tools require to be crafted. The crafting recipe for the armor and tools are 5x5 versions of the normal armor and tool recipes
brown + gray = Meteorite chunk
light blue + black = Contained singularity
blurple + black = Cosmite bar
helmet
chestplate
leggings
boots
pickaxe
shovel
axe
sword
hoe