DIY injection molding - cheap & simple grab pins

Injection moulding is great for mass-production, but it demands consistency. Moulded parts are usually designed to stay in the moving-half of the mould, so they can be quickly ejected ready for the next cycle. If a part sticks to the wrong side, the machine will stop production until an operator comes along and fixes it. (They get annoyed if this happens a lot!)
Sometimes you're faced with an awkward part - often flat, symmetrical, and with rounded edges. One method of reliably keeping it on the moving-half is to embed "grab pins" which the plastic moulds over, keying the part into place.
In this video I have a go at implementing a simple and adjustable solution, one that's suitable for use on cheap homemade moulds. I'm testing it on a 6x3x360mm strip, made from a soft polyurethane.
(Note: you can hear a bit of background crackling noise when my moulding machine is running. The machine doesn't actually sound like that. I think it could be some weird electrical interference effect being picked up by the microphone cable.)