I am trying to use plastic for a cheap and easy casting but I'm having trouble in molding it to any given shape. I'm trying to see if I can make a spark plug and want to cast out a model for measuring and getting a feel for the design. But I never worked with plastic. I'm using HDPE plastic.

  • $\begingroup$ What exactly is your question? $\endgroup$
    – Chuck
    Dec 5, 2016 at 20:12
  • $\begingroup$ Can you be more specific about the trouble you're having? Describe your current process, what the end result looks like and how it doesn't meet your needs. $\endgroup$
    – Air
    Dec 5, 2016 at 22:46
  • $\begingroup$ Sounds like you'll want injection moulding $\endgroup$
    – Jodes
    Dec 6, 2016 at 0:10
  • $\begingroup$ Any reason you don't just get yourself a RepRap and print a few? $\endgroup$ Dec 6, 2016 at 14:44
  • $\begingroup$ For general information and tips, one could search YouTube for DIY casting. There are great videos for steel/iron casting, and I'm sure there must be several for plastics. $\endgroup$ Dec 7, 2016 at 18:09

1 Answer 1


I used to make candles in the wet sand by drawing out what I wanted it to look like. I guess it would work with plastic and then grind the sand out of it.

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