The tubes come with a mixer tip, but you can get by, by pushing equal amounts of each tube on some cardboard, and mixing them together with a spreader, with out using the tip or the gun.
I do NOT do it this way,as I have all the different guns for the different types of adhesives made. Every manufacturer has their own gun. I am just posting this for the cheapest way to get the job done by a do-it-yourselfer. I am also a VERY particular auto body repairman and can do these repairs perfectly, and guarantee you won't be able to see ANY imperfection in the repair when I am done, even if you hawk eye the work. But if you don't want to pay for perfection, the job can be done for less, and you would see MINOR imperfections,.that you would also have to hawk eye to see.
This thread was asking how to fix it CHEAP, so that is why my first post didn't include the adhesive method.
There is also a brand made by SEM that has semi rigid/rigid repair adhesives.
Hard plastic bumper covers require a rigid adhesive, while a flexible bumper cover requires a semi rigid adhesive. It is very important to get the proper adhesive, for the type of plastic you are working with. There are also different drying times offered for different size jobs.