mutants and masterminds 3e – How do Quickness and Inventing/Artificer/Ritualist work(M&M3e)?

While this is possible, there are two important factors that limit the scope of how much damage someone can do with this combination (even with just regular Quickness 20): the Skill-Check required and GM ruling.

For the first part, the DC you have to meet in order to successfully create the design of the invention/ritual is equal to “10+ the Inventions Point Cost” (Mutants and Masterminds 3e: Heros Handbook, page 159), not including the Removable flaw; you then need to succeed on this check a second time to actually construct it, not to mention these are tests that your Game Master makes in secret, not by the player themselves. In any case, the upper limits of what you can pull out of nowhere is directly limited by the Power Level of the campaign you are participating in. Say, for example, you are in a PL 10 campaign and maxed-out the skill you use for Inventions/Rituals. This gives you a +20 on your roll to make a thing, meaning the only thing you can nearly always succeed on is a 10pp power (such as a Rank 5 Ranged Damage attack). If you go all the way up to a 20pp power (making the check a total of 30), you have a 25% chance to actually get what you’re asking for. At PL10, anything worth more than 20pp is statistically beyond your ability to create. Between this heavy restriction and how points-heavy particular powers can be (such as Variable, Shrinking and Summon), Inventions and Rituals are comparatively benign.

Moving on, and the more important point, the Game Master is well within their power to either veto this particular interaction or enforce the inherent limits on physically constructing a thing. Mutants and Masterminds is an extremely simple system to exploit a lot of the time, requiring a lot of oversight from the GM to make sure everyone is tuned down (or more rarely tuned-up) to an equal standard of play. Moreover, scenarios in Mutants and Masterminds are rarely straight forward brawls with their opponents; there are usually several elements that you need to juggle with combating the villains (such as saving civilians, dealing with complications, struggling against the environment, etc.). As to what the GM may enforce upon such a power, it could be limited by your access to adequate tools and the clutter-free work-space necessary to weld, glue and screw your contraption together. Another possible condition that can be enforced is the need for raw materials to work with. If you have a power to permanently Create these materials, they can rule that you’re limited to how much of a material you can produce for construction purposes each turn and/or require you to have a highly robust array of Creation powers in order to have the correct materials at your disposal.

I hope all of this helps, have fun!