[ccp4bb] RNA 3D model

[couture]

HI ccp4ers, I have to model the structure of a 400nt RNA and I was 
wondering if there was free programs out there, similar to Modeller or 
other 3D prediction program,  to predict the structure of my RNA or 
helping to built my pdb model.  I have used several programs to model 
the base-pairing and the 2D structure, but for the 3D model, I've been 
googling a lot without success.  Any helps will be appreciated.  Thanks

       Jeff