I have purchased one from Scotglas. For an upscale mosquito.

Came out real well. Still flying.

http://www.scotglas.com/index.html

As far as a custom nosecone. I watched the Team Proton
do pretty good work.

http://www.smashrocketry.com/

I am sure they would have some pointers.

Also Mark Lionberger did a great job on his Nike.

It depends a lot on what you want and how good you want it to be. If you are going to make a number of them, then you make a good one first, possibly out of wood, then use it for a mold to make a female mold, and you will make this out of fiberglass. Then you use your female mold to make a new fibreglass nosecone. That is one method. I think Ken Reilly and his son John made the nose cones for the Proton. Rich Wallner had a lot to do with it also. They were originally made of styrofoam, which was layers built up and then shaped. Afterwards it was glassed. So that is another way to get your fiberglass nose cone. I am making nose cones out of wood, when it is a big one. I design it on paper, determine set points along the way, cut out bulkheads from plywood, lay in stringers to strengthen and hold my shape, and then build it up by planking it with balsa strips or filling it in with stryofoam. If it is going to take a lot of stress from supersonic flights, then I cover it in fiberglass cloth. If it is for something like an Honest John, I look for nosecones that match the front of the nose cone up to the biggest diameter, and use that part. For the second half, I find another nose cone and take the portions I need. For the part where it goes into the body tube, I use another part and I epoxy all of this together. It is a pain, but it works, depending on how good and accurate you are.

I am sure others will jump in and tell you more. Besides Ken and John, I would seek out Larry H. and Warren for insight. You can also join the forums like www.rocketryforum.com and there will be forums on this topic. Check to find all that you can from these forums before you start asking questions to see if the answers to your questions already exist. When you do ask your first questions, introduce yourself and jump in.

Also, a lot of what you are looking for is on the internet. Your chance of success in your research will depend on how your search querry is entered, but it is there.

If you already know all of this, then my apologies for wasting your time, but it might be of value to someone else.

I hope this helps.

Try Jeff with Shockwave - http://www.shockwaverocketry.com Pretty sure he's still making cones for Tim at Apogee, among others.

And the folks at Rocketry Warehouse - http://rocketrywarehouse.com have some pretty nice cones as well.

Having done it, I can say that making a custom nose cone is a labor intensive process and the results can be questionable without serious tools and tooling to make it happen.

The main item is to make a perfectly shaped and smooth "plug" - the original from which the mold is made. The second item is to create the tooling and split mold from the plug and that is a technique in its own right. Finally, there actually laying up the cone in the mold halves and then smoothly joining them into a unit. Be prepared for a lot of work unless you have a CNC shop make your plug and mold.