Tech Tip: Big body gaps need filling? Try bubble wrap and spray foam

Say goodbye to extra-large body gaps and hello to the ultimate budget body filler combo: bubble wrap and spray foam.

When Jonathan Whitaker ran into body gaps on his $2000 Challenge Pontiac Solstice, he needed an under-budget fix.

“So, we used bubble wrap, like shipping bubble wrap, and expanding foam from Home Depot,” shares Jonathan. “The expanding foam is like $3, and bubble wrap is essentially free.”

To fill each gap, Jon shoved in bubble wrap and then coated the area with expanding foam.

“When the foam dries, it’s rock solid,” Jon explains. “You can carve it and then go over it with Bondo. It’s the perfect lightweight filler for those large gaps, and the bubble wrap gives it something to stick to.”

After a quick prep and paint, Jon and his Pontiac tore up the $2000 Challenge, finishing third overall–bubble wrap and all.

Comments

OzRaceFan GRM+ Memberand New Reader
5/9/25 2:32 a.m.

Say goodbye to extra-large body gaps and hello to the ultimate budget *ANYTHING (cars,houses, boats)* filler combo: bubble wrap and spray foam.

*fixed it for ya*

Spray the bubblewrap, or garbage bags, with water before foam cos the foam needs to absorb moisture from the air to cure.

Reason being that the plastic prevents moisture absorption, lessening the depth of cured foam. The core will remain soggy forever and eventually collapse when u cut/sand it.

If you cover the foam with plastic or plywood to maintain (mold) a particular shape, then spray that covering panel with water as well.

Depending on atmospherics, 3" per day of foam build-up is max.

Garbage bag plastic will release from the cured foam.

NOTHING WILL RELEASE FROM UNCURED FOAM!!! Your skin will be case-hardened for several days and your fingernails will be puffy for the next 5 weeks. Ask me how I know.