I printed my caps on my larger format printer in a 'fast' setting of 0.2mm layer height. This model does not need to be printed at higher levels unless you so desire.
I used 4 walls (shells), and only 10% infill. The walls provide all or the strength for the work it will be doing.
Print temps for me: 205c extruder, 60c bed.
I used a skirt just to make sure the filament was flowing before printing. On a heated bed, with PLA, you should not need a brim to hold it down. Add one if you think you do. Print it flat side down. You will need supports enabled for the overhanging lip.
The original model by biohazard3k is a great idea. I printed two of the parts and realized the extruder side cap wasn't going to fit my machine as it is currently modified. I needed to make changes for my situation.
So, I have made these remix files to share with you.
I too have used Google's SketchUp (SKP files) program many years ago when creating things from my CNC router to cut. I know of its method of simplifying ARCs to as many (or few) segments as you desire for detail. It works but doesn't have the curve I wanted.
So, with my remix, I recreated the design in Fusion 360, and leveraged the fact it uses high detail arcs, which print as smooth curves.
I also realized, there really are only two parts you need. The cap for the extruder area, and the 'every place else' cap. So that is what I modeled.
I have replaced my extruder with this part ( WK9 Extruder -- https://www.thingiverse.com/thing:2756509 ). It was designed for the Monoprice Select Mini but is 100% compatible with the Delta Mini. One thing it has are longer squeeze levers. I had to make a deeper / wider well (cage) to fit them. (** the new extruder also accepts high quality screw in Boden tube connectors.)
I also have a glass bed, and bed centering clips (as seen in one picture). So, I made a third version that cuts the 'lip' back enough to fit with those in place. (I can't find the exact model as it may have been removed, but it is very much like this one -- https://www.thingiverse.com/thing:2722596 )
All the parts have a Fusion 360 file as well so you can tweak the parts to your desires.
While I did completely remodel it in Fusion 360, I still consider it a remix because it is biohazard3k's core design.