What type of cake should be used to make this 3d cake? Please advise. I don't want the cake to sag once I stake them.D

Pound cake would be the most dense with a nice tight, crumb.

CC member recommended recipes:

http://cakecentral.com/cake-decorating-ftopict-440803-.html

The secrets of cake carving:

http://cakecentral.com/cake-decorating-ftopict-59361-.html&sid=f8dcf1a894fe2028be215fab32449e33

HTH