Customize Sprite Stretching with 2 objects?

Hello, i have a big problem:

i want to scale the tiles in my level to make it easy to make more levels. the problem is the the border gets thicker when i want to scale it:


it would be verry great if someone could help me out ^^

 

its not possible to do it like that

you will need to use extra tiles with different sprites to build that shape

2 extra tiles that you would need for example:



here is a tutorial of the correct technique

 

You can use 9-slice spites. No reason to have all that extra artwork unless you need it. You will have to judge if this is the correct solution for you as only certain sprites look good with 9-slicing.