First, you have to understand the WHY:
"why" is she harping on you about your hobby?
Women are inately jealous and possessive creatures (I'm laughing cuz my wife is in the room, hee-hee) It wouldn't matter if you were building rockets, cleaning your guns, stringing your fishing poles, etc. THE BOTTOM LINE IS, at least in HER crazy mind, that you're doing something WITHOUT HER, and she suddenly has nothing to do while you're occupied- women can't stand for a man to be content and happy; it screws up the whole female-space-time-continuum.
What worked for me was her finding a hobby of her own, which was like pulling teeth, but it happened. She took up beading and cake decorating, and they cost wayyyyyyy more than my rockets. But she loves it, and it's rewarding. Don't let your woman use that ever-famous and universal CHICK-EXCUSE: "{sigh} I'm just not talented at anything."
OH, WHATEVER!!!
My wife used to nag, but she knows how I get when I haven't worked on my rockets for a while, so she doesn't complain out loud; she harbors it just like every other woman until you leat expect it and, ....WHAMO!!! Face it, we'll never win; all we can do is ignore the nag, and keep building baby!