I have been scanning for quite a while and decided what I like to listen into, the main areas are PMR and light simple, DMR and marine.
I have purchased a couple of aerials of all types and actually think that the NOMAD put inside a waste pipe and mounted outside gave me the best all round performance. I was disappointed with the Discone and Scan Stick ones for one thing they looked unsightly and I could not mount them where I wanted, the fascia board is PVC and I do not want to make holes in it.
So I decided to make a PMR type antenna that would be light enough to stick to the plastic gutter of my house.

I had two Uniden antenna laying about and discovered that they unscrewed, the thread fits the chock block.

Added a bridge for the coax

threaded a solid core wire through the remaining terminals to bind the blocks together

Mounted the setup in a junk project box and glued it up

Measured 16cm and allowed for the little bit of the antenna that would be in the box, I was not over precise as I want to pull in the 449 and 450 bands

Marked the lengths with tape and sealed the joins...Job done!

Performance so far, I am pulling in stations that I had never RXed before, some Boefeng out the box users in town are now audible plus my DMR reception is perfect.
It works well on Air band, I hope it will still give me some service on the Marine Band, but it has been so quiet today that I cannot prove its performance as yet.