To expand on this slightly:
You get a physical investor card if you request a new one through the app. Just freeze your current one and you will see the option to order a replacement. Alternatively, wait until your current one expires and your next one will automatically come with INVESTOR written on it.
All investors should now have their forum badge. If you don’t see your the ‘Rocket’ investor badge over your avatar you need to ask for it here.
My Card arrived tuesday! Woo 
How do you get additional badges on the community forum, I still only have my Mondo Alpha badge but I think I should have Beta and Crowdfunding Investor in there too
I don’t think there are such badges. Mind you, I didn’t know about the Alpha one either. You have membership on the Crowdfunding Investers group which I believe is all there is.
I’ve got this in my profile?
Yes, I saw that. I think it’s the only bespoke badge that Monzo have created.
There isn’t a badge for beta and Crowdfunding. All badges can be seen here
I knew I’d seen that somewhere but couldn’t remember where. Thanks!
i never got my card and had to re-order… 
You aren’t sent one automatically, you’ve got to request a replacement card to get an investor card.
I haven’t posted on these forums in a long time, but though I would say hi as after missing the other chances, I’m now an Investor! I got my new card and I’m ready to rock. Not sure why I have not got the Investor description, still only says Member?
I hope you all have a Merry Christmas and a Happy New Year!
Hey Is your forum email the same as your monzo email?
Yes, it is the same email address. Weird after all this time, my profile hasn’t been updated. I even got a message in the app saying my forum profile would be updated!
Worth DMing @ cookywook
Yeah, I did that about an hour ago. Just waiting for a reply! Cheers though.
I ordered a replacement card but still hasn’t arrived. Looks like it was lost in the post, so have re-ordered one.
Sidenote - Lodged the query midday Sunday, answered first thing this morning. One of my quickest non-urgent support queries.
How long did you give it?
I ordered a card two Fridays ago and it arrived on Saturday so they’re taking a little while at the moment.
Around 10 days. But presumed that they checked that one had been posted out? I did tell them when I ordered it, so would have thought they would have told me to hold on if it was just delayed?
Just got mine!
This is a recent thing. Mine definitely used to show it on the virtual card