Once you've gathered the required materials you'll need to craft your Chemistry set. To do this click on Items
from the main menu of Team Fortress 2 and then select Backpack
Navigate to the chemistry set you want to craft. Click on the thumbnail and then select Inspect.
The thumbnail of the chemistry set will display how many items you have compared to how many items it takes to craft it.
On the next screen drag and drop the required materials from the left side to their respective box on the right.
At any time you're able to click on Apply
even if you don't have all of the required materials in the boxes. This will save the items into the chemistry set so you can save room in your inventory. The items will be consumed upon use and saved items cannot be returned.
Once you have all of the required materials in the boxes you'll be able to click on a button labeled craft
. The Chemistry Set and the materials will be consumed upon use.
Once you've clicked on craft a timer will appear. Once the timer reaches zero the item will be placed in your backpack.
If you crafted a strangifier you'll need to use it on the item it's for. To use the strangifier locate it within your backpack and select the use with
button with the thumbnail selected.
You'll then need to look through your backpack for the corresponding item that the strangifier is for. Strangifiers can be applied to any item quality variants, including Unusuals. Once you've selected it follow the prompts to apply the strangifier to the item.
When you're done following the prompts your item will now be of strange quality. The strange items track scoreboard points, which is a combined statistic of things such as point captures and kills.