I'm going to do a demo cake for a winery and really want to make the grapes and grapevines myself and was wondering if any of you know where there's a good tutorial on this? Or if anyone has any advice it would be greatly appreciated! TIA!

The first thing I'd suggest you do (if you haven't done it already) is to invest in a clay extruder - that you will, of course, only use for fondant and gumpaste! - and a grape leaf cutter and veiner. That way you can extrude grapevines to your heart's content around the cake and strategically place leaves wherever you think they'd look right. Bunches of grapes are easy to make from fondant/gumpaste (whatever your favorite medium is for this). I saw a cake like this on here once and it was really very nice. I think you could do a bang-up cake with this design! Just make sure you post a photo on this thread so we can see what happened!

I tried to find the cake I mentioned in my favorites but I couldn't, so I went to the galleries and did a search using the words "grapes grapevine" and got 31 pages of interesting design ideas. I'm sure you'll get plenty of ideas for a gorgeous cake of your own from there. I hope your cake wows them!