Or HaChaim on Deuteronomy 10:1/אור החיים על דברים י׳:א׳

1 בעת ההיא אמר ה׳ אלי, "At that time G'd said to me: 'hew for yourself,' etc." Seeing that the materials for the first Tablets were G'd-made as opposed to the raw material being provided by Moses, and that after the episode of the golden calf the Israelites were no longer worthy of such Tablets, G'd told Moses to hew them out of materials that the Israelites were able to relate to, instead of G'd providing supernatural materials unfamiliar to the people which they were unable to relate to and to esteem properly.

2G'd continued by telling Moses that he was to make a wooden ark for these tablets. The expression "make for yourself" a wooden ark does not mean that the ark would be Moses' property or would be paid for out of Moses' private funds; but, seeing that the materials the Tablets were made of were man-made, Moses was also to provide a man-made ark to house the Tablets. This is in sharp contrast to the first Tablets when G'd had not commanded that Moses bring an ark to the Mountain to house the Tablets. Seeing that the original Tablets were of material provided by G'd they did not need a protective cover such as an ark, other than the ark which G'd had commanded Betzalel to construct in Exodus 25,10. Compare what I have written on Deut. 9,17 in connection with the words מעל שתי ידי, "above my two hands." Moses was specific in repeating G'd's command ועשית לך, to teach us that inasmuch as the Tablets were really his (as opposed to the people's), it was appropriate that he be the one to construct the ark for them.