BundleBuilder
3 variants · showcase · for product, cart pages
toggle-list
the main product, add-ons with switches and a sticky total bar: the visitor builds the set one choice at a time
stack
one column of rows with an add button each, then a total card: a short list, good on a phone or in a cart
main-plus-trio
one wide main card and three small complementary cards over a band comparing the separate and the bundle prices