Yeah, a lathe definitely makes things easier, but if you are determined/cleaver enough you can still make really cool things without a lathe. e.g. the things you make plow :p.
I'll try to get a video as soon as I get a horseshoe.
Hard to say how much time I put into it, but I was out in the garage most nights for the past few weeks I think. But I also have a TV out there, so I was watching TV quite a bit too. I was also working very slowly and thinking through everything very thoroughly before I did it. As trying to redo it if I screwed up was pretty much out of the question.
It is a barrel sealing, that picture of the piston in the gun makes it look like a chamber sealing, but that was taken before the chambers were glued on.
Pretty much I got the idea to build one when my brother was taking my horseshoe set to setup at his house, and my sister-in-law mentioned that she would play if I made a launcher for them, but like I said, I'm not sure why it took priority over other projects, just something different from things I have seen before I guess is what usually gets me motivated.
On the plus side, nearly all the parts were either something I already had or something I got with gift certificates.