The ornamental design for a substrateholdingparts, as shown and described.
FIG. 1 is a first perspective view of the front, top and right side of a substrate holding parts showing our new design;
FIG. 2 is a second perspective view of the rear, top and right side view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof;
FIG. 8 is a bottom view thereof;
FIG. 9 is a cross-sectional view along 9-9 line of FIG. 3 thereof; and,
FIG. 10 is a perspective view of usage thereof.
The broken lines shown are included for the purpose of illustrating the unclaimed portions of the substrate holding parts and form no part of the claimed design.