Good screws for going into MDF or particle board.

Rok Hardware #8 x 3/4" Coarse Deep Thread Pan Head Screws Black Phosphate Wood MDF

Some decent spring nuts for 1010 extrusion

T-nut

Other screws I liked for using with nuts.

1/4-20 x 1/2" (50 Pack) Flat Head Hex Socket Cap Screws Bolts, Black Oxide 304 Stainless Steel 18-8, Hex Drive, Bright Finish, Fully Machine Thread

KOSJETHAS Button Head Socket Cap Screws Bolts, Allen Hex Drive, Black Oxide Alloy Steel 10.9 Grade, UNC Machine Fully Thread