My sister wants me to make a bass guitar cake for her boyfriends birthday.... I have no idea were to start!!!! HELP!!!

I have done two guitars. No bass though, both acoustic. I carved them both out of two stacked 12x18 sheets. traced the body of my husbands actual guitar, then scaled it down to fit the cake. Covered with fondant and painted with food coloring mixed with vodka. Made the handle out of foamboard covered in fondant. The first time I used raw pasta as the strings, that was very hard. The second time I used metallic thread, which worked much better. Hope that helps! Both pics are in my gallery. Good luck!!!

i did much like iluvjay only i didn't have a REAL guitar to trace so I just did a freeform sketch and used that as a template. I also used metallic thread for the strings and used silver thumbtacks for the part that holds the threads on.

HTH

Wow how did you make the paint splatter thingies ( can't think of a better word)?
It reminds me of those paint things that spin and you drop paint into it and end up with a multi-colored splattered circle painting?
Anyone know what those are called?

It's awesome how ever you did it!

I have done a number of guitars as well. I used many of the same steps as the other people that have responded, only I didn't have a guitar to trace. I found a picture of a guitar on the internet, printed it out, then enlarged the picture. I then carved sheet cakes using the enlarged picture. For the arm of the guitar I have done it two different ways. In one case, I used cake for the arm. For the other cake, I used rice krispy treats for the arm. I found the rice krispy treats worked much better.

I also used fishing line for the strings. I tried a few different things, but found the fishing line worked the best.

Good Luck!

That was one of the FIRST real decorated cake I ever made, still can't figure out WHY I said yes and WHY I even thought I could pull it off!!! Anyhow, I got the pics of the real guitar about 2 weeks before the cake was due (they ordered it months and months in advance) and I totally FREAKED out wondering HOW I was going to do the paint splatters!! I didn't know ANYTHING about cake decorating at all at that point...stumbled on CC and figured it all out! I wound up mixing luster dust with clear vanilla for the silver and gold and then used the powdered white food coloring mixed with vanilla for the white (titanium dioxide) worked like a charm!!!

I'm not sure what your skill level is, so forgive me if I'm off base here. I just did one also and used this website for inspiration. It also has the outline ready for you to print out.
Here is the site if you are interested.
http://www.howdini.com/howdini-video-10457955.html

You can see the one I did in my photos. I did tweak it a bit and changed the pattern somewhat to match the one on my friend's invitation. The directions here are for just a 9x13, but I did add a 9x9 to make it a little bigger.

HTH