If an assortment of items have been placed on a tray or table, some muktzeh and some not, the muktzeh status of the tray depends upon which items one considers to be more important. If the muktzeh items are more important, then the tray becomes a basis. If the non-muktzeh items are more important, the tray does not become a basis and is not muktzeh (SA 310:8). For example, let us say the Shabbat candles and the challahs are on the table. If the candlesticks are made of clay, the challahs are more important, and the table may be moved. However, if the candlesticks are silver (which makes them muktzeh maĥmat ĥesron kis), they are more important than the challahs; the table becomes a basis and may not be moved.
If one left a muktzeh item on top of something belonging to his friend, he has not rendered it a basis; as a general rule, one cannot render someone else’s possession forbidden without permission. However, if he acted at his friend’s behest or he knows that his friend wished it to be done, then he has rendered it a basis (Rema 309:4; MB ad loc. 27).
Even when the basis is much more expensive than the muktzeh item placed upon it, it still takes on its muktzeh status, since it serves as its base. However, when the muktzeh item is of no importance compared to the basis on which it was placed, the basis does not become muktzeh. Therefore, if one left small change on a table or bones on a plate, since the muktzeh item is negligible vis-à-vis the table or plate, they do not become a basis. Similarly, if the main function of the basis is not to be a basis – for example, if the door of a closet or refrigerator is attached to drawers that contain muktzeh objects – since the main function of the door is to open the closet or refrigerator and not to be a basis for what is in the drawers, the door does not become a basis (MB 310:31, 277:7; SSK 20:77).
A table that has become a basis may not be moved, but it may be used for eating or studying, as long as it is not moved. One may also expand the table or shorten it, as long as he does not use his hands to move the part of the table that has the muktzeh item on it. If the table has drawers, they may be used as well, as long as the table itself is not moved (Tehila Le-David 310:7; SSK 20:61).
. Some are lenient even if the candlesticks are silver because, in their opinion, candlesticks are merely kelim she-melakhtam le-isur (R. Akiva Eger). One should not rely on this opinion, because silver candlesticks are very expensive and therefore are muktzeh maĥmat ĥesron kis (Ĥazon Ish 44:13; Yalkut Yosef vol. 2, p. 334; Piskei Teshuvot 279:1). Also see SSK 20:61 with n. 242.There is a dispute about the status of the basis of a kli she-melakhto le-isur. Some maintain that the base of a kli she-melakhto le-isur assumes the same status as the kli itself. Therefore, one may move it le–tzorekh gufo or le–tzorekh mekomo (Tehila Le-David 308:1). Others maintain that since a kli she-melakhto le-isur is not completely muktzeh, it does not render the base supporting it a basis at all (Yeshu’ot Yaakov; see SSK 20:50). Since muktzeh is a rabbinic law, the halakha follows the more lenient position.
If a desk or table has a drawer that contains muktzeh items of significance, then if the drawer can be completely removed from the table, the desk becomes a basis for the drawer and may not be moved (similar to the case in the previous note of a money pouch tied to clothing). If the drawer cannot be removed from the desk, then it is secondary to it (as a pants pocket is secondary to the pants), and the muktzeh items in the drawer do not render the desk muktzeh. In any case, the drawer itself is muktzeh because it is a basis (MB 310:31).