Coinsandcanada.com

Hi. I have a 1943 brown "penny" coin that is 12-sided. The Reverse has a Canadian 1 cent profile wihle the Obverse appears to be a British 3p profile. Thoughts on whether to classify this as a Mule or a Planchet error? Thanks.

We will have to see clear photos of both sides before determining what you have.
It would be impossible though to have what you are describing.
Canadian 12 sided coins didn’t start until 1982

My mistake. I did an internet search on a 12-sided coin and it came back with the 1943 3p example. The Obverse image on both the British and Canadian coins are the same. It is, however, 12-sided. I'll post a photo as soon as I figure out how to do it. Thank you.

Here you go, hope the quality is reasonable.

That looks like it was intentionally done. See how uneven the length of each side is.
On a 12 sided coin, the sides are equal. Keep it as a novelty coin.
Also if you look closely, the wording is different on a Canadian vs UK coin.

Neither mule nor error.
Someone put in a lot of effort to make this.
It' a cool keeper for sure.

Coinguy and TBH, thanks for taking time on a Sunday to provide input. My father was an adid collector and has a pretty good collection of errors, I think. Problem is that he saved everything that came across his desk and now I'm validating.

Definitely a damaged coin, but these sometimes make cool conversation pieces. I use these when teaching collectors about the 'third die', the collar die and how to differentiate fabrications from real errors.