Portal Grenades?
Now:
Your talking about bugbait, and changing the decal, bassicly: coding. I think what we are trying to do here is create something people can use by just downloading a map, not a mod. anyway just changing the decal will just make a portal decal which you can not enter ....
no. change the decal to a portal thing. not a portal decal XD
and did you not play bluestrikes map? he coded those ball-things into the map. it's easy enough :3
I think if its possible to add portal beforehand and disable it in hammer. also have trigger_multiple with settings that when the grenade explodes in it it will enable that portal. That of course if you have only one portable area in room, or you have one of these for every wall... But that's kinda fake 
and did you not play bluestrikes map? he coded those ball-things into the map. it's easy enough :3
Oh, of course 
Now i don't think i've played his map but you mean this idea has been done before? (Shooting evergy balls from the portal gun). I already made that work with a simple bind.
OF COURSE! GOOD IDEA! You may think it's kinda fake but if it works and it doesn't look too bad, then it's cool. I think im gonna try this :3
not energy balls. I meant an entity etc. was coded into the actual map. it was a giant weighted storage cube-themed ball.
as i don't know loads about this i dunno if this is possble (or already been said but i just havent undersatood it) but isnt there an obeject the can creat a portal? like an entity which is placed somewhere u want a portal to appear if u press a switch etc (if say you only have one half of the portal gun...)
mabey you could have it so that one of those entities is created by the grenade..
looking at the wiki its a prop_portal...
if it cant be created by the grenade "exploding", mabey you could have it off the mapp, and then when the grenade "explodes" it's location is changed to the place the grenade is...
another problem with this is that you would have to make sure that the grenade can't explode on metal...
if you can get this idea to work it would be really cool 
that is a VERY good point 
idk how that would work. I'd imagine some heavy coding 
idk how that would work. I'd imagine some heavy coding
You never realized you can make new mechanisms with hammer did you?
Where do you want to code it?
mabey you could have it so that one of those entities is created by the grenade..
looking at the wiki its a prop_portal...
if it cant be created by the grenade "exploding", mabey you could have it off the mapp, and then when the grenade "explodes" it's location is changed to the place the grenade is...
another problem with this is that you would have to make sure that the grenade can't explode on metal...
if you can get this idea to work it would be really cool
That's a good concept. Perhaps it's a good idea to combine this with a trigger, like penapappa said. You could then cover all portal-compatible surfaces with triggers that move your prop_portal to the location of the impact AND orient it correctly for that wall or floor. (That's kind of important, as the prop_portal doesn't do this on its own.)
Of course you can then prevent a portal from landing on a metal or glass surface by just not placing a trigger there.
I would love to experiment with this, but i'm currently tied up with my next map pack which, among other things, involves a pretty complicated laser thingie. (Did you know that an env_laser doesn't go through portals? 
)
Other Portal 2 maps: Medusa Glare
Portal 1 maps: Try Anything Twice | Manic Mechanic
glad u like the concept...
expanding on ideas:
if you cover an portalable surface with a trigger_multiple you can have the grenade check for collision with the trigger. if that is passed then the grenade creates a prop_portal in that location (just realising next difficult may be portal bumping. not sure if a prop_portal could be bumped... i would say not...). That prop_portal then creates a portal in that location...
i will mabey try give this a go (or something similar...)
I think exlposion is good on the orange grenade and then the blue one should have a different effect.