I do this right regularly. I created a huge trash can shape container using 8 separate pieces printed in PLA. I then glued together with CA glue and welded the pieces with a 3D pen to make the joints stronger.

A couple of things to remember:

3D pen don’t push the filament like a 3D printer does. You have to slow the flow of the pen down, and let the filament bind to the layers below

There’s a big difference how different PLA will behave with a 3D pen. Some filaments won’t stick as well like others

You have to mimic the behaviour of a printer with the pen. So you have to lay down layers of filament, rather than trying to make it behave like a glue gun.

I bought a Canon Pixma TS705a simply because I wanted a small footprint, no scanner and relatively cheap ink. I can replace all the cartridges for about $11 if I buy the cheaper brands of Amazon