Abrahams 3 angelic visitors.
Genesis 18:1 Afterward, Jehovah appeared to him among the big trees of Mam′re while he was sitting at the entrance of the tent during the hottest part of the day. 2 He looked up and saw three men standing some distance from him. When he saw them, he ran from the entrance of the tent to meet them, and he bowed down to the ground. 3 Then he said: Jehovah, if I have found favor in your eyes, please do not pass by your servant. 4 Please, let a little water be brought and have your feet washed; then recline under the tree. 5 Seeing that you have come here to your servant, let me bring a piece of bread so that you may refresh yourselves. Then you may go on your way. At this they said: All right. You may do as you have spoken.
6 So Abraham hurried to the tent to Sarah and said: Quick! Get three measures of fine flour, knead the dough, and make loaves of bread. 7 Next Abraham ran to the herd and chose a tender and good young bull. He gave it to the attendant, who hurried to prepare it. 8 He then took butter and milk and the young bull that he had prepared and set the food before them. Then he stood by them under the tree as they were eating.
2 of those angels went onto the city of Sodom, they stayed with Lot and his family and took Lot by the hand to take him out of the city before it was destroyed:
Genesis 18:22 Then the men left from there and went toward Sod′om,...
Gen19:1 The two angels arrived at Sod′om by evening, and Lot was sitting in the gate of Sod′om. When Lot saw them, he got up to meet them and bowed down with his face to the earth. 2 And he said: Please, my lords, turn aside, please, into the house of your servant and stay overnight and have your feet washed. ...Then he made a feast for them, and he baked unleavened bread, and they ate.
4 Before they could lie down to sleep, the men of the citythe men of Sod′om from boy to old man, all of themsurrounded the house in one mob. 5 And they kept calling out to Lot and saying to him: Where are the men who came in to you tonight? Bring them out to us so that we may have sex with them.
...15 As dawn was breaking, the angels became urgent with Lot, saying: Get up! Take your wife and your two daughters who are here with you, so that you will not be swept away in the error of the city! 16 When he kept lingering, then because of Jehovahs compassion for him, the men seized hold of his hand and the hand of his wife and the hands of his two daughters, and they brought him out and stationed him outside the city.
There is also the account about Jacob and how he wrestled all night long with an angel in order to obtain a blessing from God.
Gen 32:24  Finally Jacob was left by himself. Then a man began to wrestle with him until the dawn broke. 25 When he saw that he had not prevailed over him, he touched the socket of his hip; and the socket of Jacobs hip was dislocated during his wrestling with him. 26 After that he said: Let me go, for the dawn is breaking. To this he said: I am not going to let you go until you bless me. 27 So he said to him: What is your name? to which he said: Jacob. 28 Then he said: Your name will no longer be Jacob but Israel, for you have contended with God and with men and you have at last prevailed. 29 In turn Jacob inquired: Tell me, please, your name. However, he said: Why is it that you ask my name? With that he blessed him there. 30 So Jacob named the place Pe·ni′el, for he said, I have seen God face-to-face, yet my life was preserved.
31 And the sun rose upon him as soon as he passed by Pe·nu′el, but he was limping because of his hip. 32 That is why to this day the sons of Israel are not accustomed to eat the thigh sinew, which is on the socket of the hip joint, because he touched the socket of Jacobs hip joint by the thigh sinew.
There is also the account in Genesis about the Angles who came down wrongfully from heaven and married woman and had children.
So angels really can materialize into human bodies. But im sure you agree that we cannot de-materialize and become spirit, right?