I bought a cheap pen, maybe the same as the other poster, to help weld things together. Turns out I have no skills, and it looks bad. As a whole for me, 3d pens are annoying to use.
When you need to weld two 3d printed parts together, try Weld-On 3. It comes with a hypodermic applicator. Press the parts tight together, then drip some Weld-On 3 in the seam. The liquid is a strong solvent that dissolves the surface of both pieces, but within a minute the parts are welded together. It's the BEST way to weld two 3d printed parts together I have ever used. Use in a well ventilated area.
We use a 3Doodler Pro+ at work, which I think might be the most expensive one out there? I've got to say, it really isn't any easier to use than the cheapest alternatives on the market... There's just a horrendous learning curve to these things in general, although if you think of it as any other art form then I guess it's probably comparable.
On ours, I do really appreciate the wide heat range, the ability to access the dual gear extruder during operation, and the swappable nozzles. What I don't appreciate is the ridiculous markup, the non-standard nozzle size, and them lying about only being able to use their special proprietary filament (it's just normal 2.85mm).
I have this pen which is $60 on Amazon. I really like it. Used it with PLA PETG and ABS with no issues. It doesn’t need as high temperatures as 3D printer as the filament comes out much slower.
I’ll look for some examples tomorrow. But along with free handing sculptures, I’ve also used the 3D pen as a welding machine for my 3D prints. You can use it a bit like a tig welder, making welds to connect two parts with the same material and color as the print. It can be completely invisible with sanding afterwards. I also used it to fill in cracks in other things that broke. It’s both fun and super useful for functional parts.