What is the best way to make a koi pond pump?

I would like to help you but your question is too open ended.

I have had 3 ponds in the last 45 years, the first was very little and did'nt

last long, the second one was bigger but had several problems with animals

eating thru the liner (musk rats). the third lasted over 30 years.

I made just about everything for my ponds but the liner and the pump.

So if you want to know how to make a pump, well I guess your on your own.

But if you mean the filter then maybe I can be of help, its true you can make a better filter then you can buy if you smart.

I would first need to know what it is you want to make.

Then how many gallons the pond will hold, and if you plan to use a bottom

drain. By the way if you intend to have koi you should really consider the bottom drain. R