Since the 1.359 update to Banana Shooter, items have had a rarity score associated with them. metotallynot (on Discord) compiled a list of the rarity scores for each parameter (rarity, colour, shiny and particles) and I've used it to create this program which you can use to calculate the rarity score for any possible cosmetic item
The program is very self explanitory but just in case this is here to show you how. Upon opening the program, you will be met with this interface
From here you can select the item of choice from the dropdown, the colour of choice from the dropdown, the shiny value of choice from the dropdown and the particle of choice from the dropdown. After this you can press Calculate score to calculate the score. In the below example I chose a Light Blue, 0.1 Shiny Alien Face with a Stun Particle, which has a rarity score of 17 as also shown in the subsequent in game screenshot
