For my twin sons 6th birthday, we threw a Harry potter party.  For invitations I photocopied a picture of Hedwig onto white cardstock, then cut it out leaving a tab below her claws. I then made parchment" (crumpled regular white paper and dipped it into tea dried then ironed it flat so my printer would accept it). I printed the following 2 per page with the Hogwarts crest at the top of each column. "Dear ______  We are pleased to inform you that you have been invited to attend the Hogwarts School of Witchcraft and Wizardry for a special celebration of (my sons names) 6th birthday. The celebration will take place on _______ from___ to ___.  The magic will begin at Platform 93/4 better known to muggles(non-magical persons)as (our address). Please RSVP no later than ____ so that Hogwarts can make all necessary arrangements for your classes and supplies.  You can do so by sending an owl or calling _____ on a muggle telephone.  Sincerely Minerva McGonagall Deputy Headmistress". I then rolled it up to create a scroll tied it with a ribbon and glued it to the tab on the bottom of Hedwig's feet.  These were hand delivered at school and all the kids were really excited to get "owl post".  For decorations we used purple gold and black streamers and balloons and made candles out of white and orange cardstock which we taped to the walls and suspended from the ceiling with fishing wire. I painted posters of the Gryffindor and Ravenclaw crests and the fat lady.  My sons coloured Harry Potter colouring pages which we found online and we also put those on the walls and made them into signs to designate different areas (i.e. the dining room was "potions class" play room "transfiguration etc.) We also put cobwebs and plastic spiders and rats all over. Outside we put a sign saying "platform 9" on one side of our driveway and "platform 10" on the other our front door had a sign saying "platform 93/4" with a picture of the Hogwart's express. The birthday boys were dressed in Hogwart's robes(purchased on sale after Halloween)dress shirts and ties and the grown ups were also in character as Hogwart's professors in our robes and various other accoutrements. As each kid arrived one of my sons would lead them to "Diagon alley" (through a brick wall we'd made out of a large piece of cardboard which one of my sons would have to tap with his wand just so to get to magically open). Once there they'd be instructed to first go to Gringott's and make a withdrawal (a chest set in front of a Gringott's sign with an envelope for each child containing plastic gold "galleons") then to buy their supplies.  I had made simple robes out of cheap black fabric which the kids "bought" from Madame Malkin (my sister) who measured them with a tape checked their eye colours etc. before selling them a robe. Next Ollivander's for a wand.  I made wands out of bamboo chopstickspainted different shades of brown then wrote with black marker things like "mahogany and dragon heartstring" or "oak and unicorn hair". My husband reminded each child that "It is the wand that chooses the wizard" then had each try out several wands on a stack of cans (wrapped in purple and gold paper) that we had attached to some fishing wire and wrapped around a hook.  If it was the wrong wand my husband would jerk the wires behind his back and the cans would come crashing down. If it was the right wand he pulled the strings gently and the cans would magically levitate. It was a huge hit! We had my sons choose their wands before their guests arrived so they could each have lots of time to get just the right one (like Harry's of course "holly and pheonix feather"). We had early arrivals work on some HP colouring pages while everyone made their way through Diagon Alley.  When everyone was outfitted it was time for the sorting.  We had a stool with a baby monitor hidden underneath and an old witches hat on top.  My husband hiding downstairs read out scripted comments as I called each child's name and they put on the hat and we divided them into 2 houses Gryffindor and Ravenclaw (my sons favourites). We then took each group to 3 different classes. Potions was the BIG favourite. My husband in his bathrobe and a black wig as Professor Snape had the children make the "Sillius Silvanus Potion" (a potion to make you silly).  We had ingredients like crystallised lion tears (lemonade mix) powdered eel (blue kool aid pre-mixed with sugar) dehydrated lava rocks (pop rocks this was the crucial ingredient it really makes the potion fizz and crackle) flobberworms (gummy worms) dragon liver (red jello jigglers). He had them mix up their ingredients in plastic goblets then poured club soda over it all then they had to stir it tap it with their wands and say some silly words.  They loved the potion and my husband never broke character as mean and nasty Prof. Snape which the kids also loved. We also had Transfiguration class transforming a piece of black paper into a wizard hat and Divination where they played pin the star on the constellation and did jelly bean divining (similar looking Bertie Bott's beans in a cup the kids had to guess whether they'd gotten dirt or cinnamon or spaghetti or cherry etc. We had kleenexes nearby for spitting out the yucky ones).  After that a feast in the great hall. I had the tables decorated with more jellybeans and paper stars and we used gold paper plates and cups.  We served chips cheddar pasties (mild cheddar melted on puff pastry) and fruit wands (skewered fruit).  We offered pumpkin milkshakes or juice to drink (the pumpkin shakes were NOT popular). For the cake we had 2 plates of chocolate cupcakes which had the candles for each birthday boy to blow out and a huge rice krispy castle (tinted the melted marshmallows grey with black food colouring to make it look like stone had chocolate covered sugar cones upside down for turrets a chocolate drawbridge and used chocolate icing to make windows etc.and served it on a platter iced green for grass with more sugar cones iced dark green for trees and little figurines of Harry Hermione and Ron).  It was dead easy and looked impressive. After the "feast" we had a wizard themed puppet show to pass the time until pick up time.  As each parent arrived we called the children up to spend their remaining galleons (we made sure they had lots) at "Honeydukes". We set up a candy store with tubs of gummy spiders and rats licorice "wands" etc. I also made chocolate frogs with a mold I'd purchased on Ebay which I wrapped in cellophane with a wizard card.  Into each candy bag we tucked a report card which gave marks for each of their classes (wouldn't you know it they all did outstanding!) and a thank you from my sons along with a web address they could go to the next day to see pictures posted from the party (we did the web page with a "daily prophet" theme). As a last treat we handed out dragon eggs. Using balloons as molds I had made paper mache eggs which I put toy dragons (fierce looking ones for the boys and cute ones for the girls) and a few wizard stickers in then sealed up and painted. We attached a note with a picture of Hagrid explaining that this was from him and how to take care of a baby dragon. This party was a lot of work and a lot of fun and a huge hit with all the kids especially the birthday boys. They were all still talking about it months later. I got a lot of ideas from this website and of course the HP books and movies."