Thanks to everybody for their input !
I was at a photography store a couple of days ago asking for a metal hood, and they only had the collapsible rubber one (the plumbers plunger as I described it). Because it was fairly cheap, I bought it because I didn't feel like waiting around for a generic one to arrive from China.
The rubber hood seems to be okay, and its quiet convenient in that it collapses when storing (and not for collision sake). The metal component that screws onto the lens is not a matt finish and has a shiny finish - which is not quite good enough. All in all it seems to work okay, the lens itself is producing a very nice 3D effect at f/1.4 and to me it doesn't seem to flare too badly even when the sun is in image:
https://www.pentaxforums.com/forums/members/54618-zoolander/albums/6230-pent...ture54935.html
One guy has stated in the lens review for this lens that he owns the FA 50mm f/1,7 and the f/1.4 is just as sharp when you use a hood - so this is up for debate - but I'll take his advice on getting a hood.
I'll order a metal 1.5 or 2 inch one as suggested by some of the folks above anyway because I have other Pentax lenses which are need of having a hood. I'll test it out and remark on this thread when it eventually comes.