I can't remember the names of the parts, but I was able to by metal replacements at a specialized hardware store (i.e. not a regular big box Home Depot). I just went in, showed the broken pieces and asked what they had.
Yeah, you can get them at the hardware store but they are surprisingly expensive and Ikea will replace them for free.
I work for a company that makes RTA furniture and honestly, there really isn't much of a difference between the metal and plastic cams. The metal ones are cast and typically very brittle. The plastic is more resilient and will last a long time.
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