I have good luck using the MP Jet aluminum spinners for electric motors on our small IC engines. They are available in 30mm and 40mm diameter and I get mine from www.icare-rc.com and they are not expensive.

I have made adapters to fix a variety of Cox 049 reedies and TD's and AP .15 and have also modified the spinner back plate to fit larger size engines PAW 1.49CC / 09 and 2.49CC diesels.

I have a small lathe which helps.

see this thread for some details on the reedy versions:

http://www.rcuniverse.com/forum/m_42...tm.htm#4258386

and just the pictures:

http://image.rcuniverse.com/forum/up...87/Ca80598.jpg

http://image.rcuniverse.com/forum/up...87/Ni24196.jpg

http://image.rcuniverse.com/forum/up...87/Xc79316.jpg