Arjuna can project objects for days with little cost.

Ah, the field of magic dedicated to creating stuff from absolutely nothing. Great for pranks, toys, acting out movie scenes (Like that one scene in Aladdin, when Genie first meets Aladdin and starts singing), and having literally anything imaginable on your person at all times so long as you had the prana for it! Best of all, it's stupidly cheap by its very nature so now that you have your Circuits unlocked completely you can use it all the time! Now if only you had a way to make your Projections last longer without looking like you're disintegrating in slow motion...

Your first avenue of research is to give your Projections a conceptual 'history', a sense that these existences are natural to the world and therefore should be ignored by Gaia. It's actually a great deal easier than diving into the conceptual frameworks of objects...though that's not saying much, if you're honest.

On the other hand, it's practically as easy as safely Reinforcing things is for you at this point-and even though Mikolov's book swears up and down that Reinforcement is a delicate and precise art that can backfire on you at any moment, you've never had an accident with it yourself. The big baby was probably exaggerating.

Weaving an entire fictional history for your objects is simplicity itself, and connecting those fictional histories to your objects is the easiest thing in the world. Even better, when you read into the Projections you created, you can actually watch as Gaia apparently gently corrects the few inconsistencies in the histories you design as if the planet itself can't tell that your Projections haven't always been there. With that evolution in your Projection skills the lifespan of your Projections spontaneously jumps from hours to days with no change in the prana cost or even the casting speed-frankly, you might've gotten a bit faster even.