How to cut STL models for 3D printing in Meshmixer - Prusa Printers
Explains how to slice a model in Meshmixer and add alignment pins.
For infill, do what you feel is right. Initially I printed with lots of infill 25+% because I was worried that it wouldn't be enough. Since then I've stepped it down over time depending on the model and expected use. Many of my prints I stick to around 5-10% infill now and have been perfectly fine.
As far as plastic type goes, again maybe not so helpful, but use what you want. There are pros and cons to each. ABS seems to be faster to sand, but there are a lot of different factors into if that's true or just feels easier.
3D Printing Nerd and Punished Props did a video comparing sanding parts printed with a few plastics starting around 7:05 will get you to PLA vs ABS.
Due to the lower temperature required for PLA to melt vs ABS, PLA prints are more likely to warp when left out in a car. I recall Punished Props doing a
Boolean Gemini from Destiny that warped when left in a hot car, but we deal with that issue for almost any method of building (looking at you foam and hot glue).
There's also the matter of temperature fluctuations affecting ABS and the temperature needed on the print bed and hot end for ABS vs PLA. ABS tends to warp
I would say if you have a lot of one over the other, use what you have. If you haven't bought filament yet, have an enclosure, and want something that's possibly easier to sand and will be more resilient against being left in the car, then I'd go with ABS. Even with that said, I'll tell you my current projects are being done in PLA because I'm printing them on a printer that doesn't have an enclosure (yet) and am concerned about warping during the printing process.
