the downside to making a custom FMIC is that they usually cost alot more then the name brand companies FMIC kits. If they are cheaper, they are probably a lot less efficient, will slow down spool, and are probably purchased as universal kits on ebay. If your going to go custom, buy aluminum piping and get the ends rolled, 4 ply silicone couplers, t-bolt clamps and a good core like spearco