Cutting a Competitor to spade shape? OR making a spade shaped monofin?

[Red]

I have a competitor I never use and deeply want a spade shaped monofin. Is there a way to cut/shape the competitor to that shape?

If not, any idea the best way to make one for use with fabric tails?

My ideal shape Fluke for the Competitor is number 8 from the choices in the picture below. If that's not possible number 5 is my second choice and looks easier as it's closer to the competitor shape. In both cases I want a single solid fluke, no split so ignore the lines that look like a split. As for needed advice, I'm incredibly handy, a costumer with alot of tools on hand and live for DIY, so if anyone could explain the process clearly for either cutting the competitor or making my own it would be deeply appreciated!

Should this be impossible either way, if anyone knows someone who makes custom shaped monofins, please send their info my way!

Thank you all for any help, this is my first post (longtime and fervent reader though 😊).
https://cms-assets.tutsplus.com/uploads/users/108/posts/21955/image/how-to-draw-fish-2-4-fin-shapes-types.png

[Mermaid Jaffa]

Why not get a no 5 shaped monofin (Finis rapid, wave, foil, powerfins) and make the tail fluke with a flowing point so it looks like no 8.

[Echidna]

I know people have done this using a dremel.
Be careful to not remove the side ridges though, that would cost you most of the propulsion.

But it's totally doable with the right tools.

[Red]

Actually less propulsion would be ideal frankly. I live in a wintering land-locked place and have never used the competitor because it's got way too much propulsion. How much would it lose , ideally it would go no faster than a Linden once cut. I own a rotary tool that could perform the job, unless you meant a more specific dremel tool? I love the spade shape and as I make dynamic fabric based tails, I'd love a genuine spade monofin over pvc casing tricks. I'm nervous I could crack it or somehow compromise it's integrity for use. Any tips for an ideal outcome? My rotary is not a extreme model or anything , though I have access to better tools need be.