Body panels
 

Am changing the radiator fluid in my 98 Boxster. Car does not have the plastic panel under the car that covers the radiator hoses. Does anyone have a full size drawing/template of one or have the full specs on one so that I make that piece? How important is it to cooling or aerodynamics? Or can I just buy one somewhere - for not too much money? Thanks.

You can find them here:
1998 Porsche Boxster Base Convertible - Chassis Panels & Sheet Metal - Page 4

Try itsnotanova (on here) for a used one.

Surprisingly affordable
 

I would never attempt to make one for those prices

They are not really that expensive

UNDER COVER & SPLASH SHIELDS for 2004 Porsche Boxster

I'm thinking the last belly panel is not really that important as 75% are missing from the boxster that I get it and 20% are broken and barely holding on. I've only ever had 2 boxsters come in that had a rear belly pan that wasn't broke.

I ended up replacing all but the front belly pan on my 2001 S. They're really nothing more than splash shields.

They aren't all that expensive.

I'd recommend just ordering a new one - it would take forever for you to duplicate all the bends and stuff for that rearmost cover. Check the PET for part numbers, but you'll also need a couple of those 10mm plastic nuts (like those used for the rear wheelwell liners) that attach it to the body, four sheet metal bolts that attach it to brackets on the big aluminum reinforcement bars, and then there's also a 10mm nut that attaches it to a stud in the middle of the car.

Thanks for the guidance. It's the rear splash cover (closest to the oil pan) that is missing. Now I just have to decide if I really want or need one. I'll do some shopping.