stray cats claw at my screen and put hole in screen

I have 4 stray cats who adopted me. they love to sit on the narrow window ledge outside and look in the window. They scratch on the screen and claw at the window. This window is on the front of the house and now there is a big hole in the screen. how can I stop them from doing this? I placed gray tape on the little ledge hoping the stickiness would deter them and the heat during the summer months has cause the tape to melt on the window. now I have this gray stuff all over the ledge and it won't come off. Is there anything out there that I can get to adhere to the narrow ledge so when they jump up to look in the window and scratch, they wont like whats there so they will jump back down. I want to buy a new screen but I will have to solve the cat problem first. the screen can not be switched out to a window in the back of the house because of size difference. thanks in advance.

A free solution would be to scatter lemon peel on the window ledges. Most cats hate citrus. The next step from that is to get some lemon essential oil, put some in a spray bottle with water (1 drop oil to 10ml water) and liberally spray onto the window ledges and screens. You will need to regularly repeat the spraying, but it's cheap, invisible and won't hurt anything.

Cats hate to walk on aluminum foil, you might see if it will stick to that sticky ledge.(WD40 will get that sticky off) If all else fails, get a strip of that clear plastic rug runner, found at most dept stores and Walmart, and put it so the little plastic 'grippers' on the back stick upwards, cats won't walk on it, it hurts their paws. They love you so much they want to be with you!

you can get pet-resistant screens 

thanks for responding,  the screens I have are custom made screens I had made when I had replacement windows custom made for my house. I don't think I would be able to get custom made cat resistant screens made. that would be expensive. but an excellent suggestion. thanks

thanks for responding. I like the rug runner idea. but how would I attach the plastic runner to the metal part of the window?. these are not wooden windows. they are thermal replacement windows I had installed several years ago. thanks

I will try the lemon spray. I will check on eBay to see where to order. thanks for your suggestion.