Building a 1/35 RPG

The projectile looks like it would be easiest made from stretched sprue. Heat both ends (separately, of course) and pull slowly until both ends look correct. The RPG grips could be stolen from any one of the weapons kits such as the M16 family set, etc. They might be close. Metal tubing would make a nice firing tube as it is thin. Use different sizes that telescope together to get the right look. For the exhaust tube, anneal the metal tubing and it will allow a nice flare; work slowly with a pointed wooden dowel of small diameter. 

I don't know if this would work for you, but there are some pen tips that could be cut and sculpted to meet your needs.

Just a thought. 

Passing thought - get a couple of panzerfausts, one of the smallest ones and then one the next size up.  on the smallest one, cut off the *front* of the projectile and then cut the launch-tube farther back at an "appropriate" (read that as "looks good to me") length.  This will be the front of your PG-7 grenade.  then repeat the process with the larger Pzf. - with or without a section of launch-tube - to make the rear of the PG-7 projectile.  (If your launcher body is a tube with an ID large enough to hold the Pzf launch-tube, then you could make it where the PG-7 actually loads/unloads!!  Action-toy!!)  So, you have two butchered panzerfausts with flat noses.  Glue these two flat areas together.  Paint appropriately.  Voilá!  Pseudo-RPG!

Use this advice at your own risk, I am not an expert.  I have never attempted this exact procedure in person.  If you would like more real-world reference info on the RPG than you will EVAR! use, let me know and I can help you out w/ a couple of sites.

I don't model in armor anymore, but do remember buying one years ago made out of white metal(along with some AK's). I may still have it somewhere. Have you tried an after market source?

Edit: I found the AK's and the placard they came in, but no RPG. They were, however, from Verlinden, so you might check their site.