Kitbashing started with model enthusiasts, who were eager to create models of things not already commercially available. So they would take parts of several commercial model kits and "bash" them together to make their dream model. This might be as simple as customizing a staid family car model with parts from a dragster, or as complex as creating something never seen before in any form. The original Star Wars X-Wings are an example of a rather involved kitbash, being made from pieces taken from model ships, tanks, planes and other pieces the fabricators had lying around. Thus, kitbashing is the art of taking elements of what's readily available and making something of your own from it. Kitbashes on my webpage vary from simple repaints to major rebuilding projects.
Okay, so that's what kitbashing is. How does that apply to a philosophical stance? Well, think about it. Life rarely gives you exactly what you want. You basically have three options when you don't get what you want out of life.
One of the big things that kitbashing helps with is getting over the fear of "messing up" things. In order to make something new in a kitbash, you have to change something old, and you do risk ending up with nothing if you destroy an old thing but fail to make a new thing. Since most of what I work with in kitbashing toys is cheap (I scour clearance racks for cheap toys to modify), I can ease into getting over that fear. After all, if I do mess up, it's only cost me a couple bucks and some effort, right? But recently I've been daring enough to tinker around with far more expensive toys, fixing problems and overcoming deficiencies. And as I continue on this path, hopefully I'll get more and more comfortable with the idea of altering important things in my life, for the better.
As long as we fear change (and modern Western society seems to encourage that attitude), we're not going to be able to overcome anything that needs changing. And if some paints, tools, sculpting compound and cheap toys can help someone ease into being comfortable with change, so much the better.