Ditto on the Lee Bottom pour pot, and the advice given so far. Here's another safety tip: ALWAYS make sure that your ingot mold is BONE DRY and heated before you pour. I found this out the hard way--thank Almighty God I was wearing heavy gloves and a heavy coat, with safety-rated glasses! I had the ENTIRE contents of a 10 pound ingot mold literally explode at me--if I hadn't been wearing the glasses, I would have lost at least one eye; had I not been wearing heavy gloves and clothing, I would have suffered deep tissue burns over my back and entire right arm.
Never get complacent--ALWAYS use good safety procedures.
To initially smelt and clean your wheelweights, I heartily recommend a seperate burner, like the propane burner and stand arrangement for a turkey cooker. Use a cast iron pot to melt in--I got mine for $5.00 from Goodwill.
Use a small pot--even the small ones can hold 20-25 lb. of molten metal.
Be VERY aware that moisture is the enemy--even including the grease still left on the wheelweights.
Fill your pot, turn on or turn up the burner, and stand BACK. Wait until it's melted, COMPLETELY.
Now, fish out the metal clips--they will float up to the top. I use an old steel, wooden-handled spoon with holes drilled in. Dump these into a coffee can, or other metal container. Let the melt stabilize.
Now, flux the mix. Use a small amount of flux--I use Marvelux from Brownell's, and it works well. Wait until it melts, then stir it in steadily. After the crud gets to the top, skim it off.
Now, put your ingot mold on the ground. I recommend laying down a sheet of plywood, if you do it on concrete--no matter how careful you are, you will get some on the concrete, and the wife will give you the devil for it. Don't ask me how I know...
Pour the ingot, and LET IT HARDEN. When you can tap the side and see no jiggling of the melt, it's safe to dump. Dump it out, and do NOT touch it! It will be REALLY hot for quite a while.
After you pour as many ingots as you would like, I recommend spraying down the ingots with water from a hose. This will ensure that they are cool enough to handle. Wipe them off with an old towel that you will NEVER use for anything else, and store them. You're good to go!
For more information that you may need, some time ago I posted a quick guide to starting out in bullet casting. You'll find the first post here:
http://www.thefiringline.com/forums/showthread.php?t=167211&highlight=Bullet+Casting+A+Quick+Start
There are four parts to this post. Hope you can use it!