Does making your own tools make you less likely to get caught?
For example for a virus than coding you're own instead of using a using a very well known virus (or generate one with a well known virus generator) can make you stealthier against AV.
If you are coding a tool for ARP Cache Poisoning then no because this tool will be very noisy on the network by nature.
Depends,you can have great coding skills and use them to write a perfect tool/malicious program to evade AV's detection, debug and update it, but of course that will take much more time/effort than using someone's tool. You can use someone's tool without knowledge how it works/operates and you can bypass most of AV.
This is an interesting question.
From a forensic perspective, using common tools is harder to trace and harder to attribute to you. If many people have access to the tool, then it is harder to know who is behind the attack. If someone skilled at Python writes a unique Python attack tool, it stands to reason you're looking at someone with a background in or preference for Python. By observing what you use, avoid, and prefer, one can create a fingerprint in the code that you write based on your level of skill, geolocation, and culture, etc.