So it's kinda hard. I'd recommend getting just a free sample tile from a store (it's like $2 for one tile) and an overhead tripod like this one (there are cheaper options, just search "overhead tripod" on Amazon). It makes pulling (especially) and filming slimes SO much easier. I find this might be easiest but I made a mistake and got the wrong stuff so will have to change eventually. Film in a space with lots of natural light (like by a window) on a table with the tile. Clip the tripod to the end of the table and voila!

Or if you're interested in short form filming, you can just get a normal one like this at Dollar general or whatever to show your face and film other videos (which is what I use)