They have got to be kidding me.. apparently there is a limit on what one can spend on this project - of $35. Yeah, I get why there needs to be a limit, but $35?
How much is a big poster board now? $8? Sorry kid, but your display board just took 1/3 of your project money. So Thermoacoustics it will be - probably can do refrigeration or electric generation, but not both, and no you can't use your Father's PC based Oscilloscope, or PC based signal generator. much less the bazillion project materials he has lying around ( switches, transformers, hookup wire, heating element wire, etc) because you have to provide a receipt for it all. After all, this is public school, and you should be prevented from actually learning anything by your budget - which is too small to buy the family a single meal at Chili's. . Calling it a science fair is just a ruse to make others think you are learning science.
SO Yeah, I am still figuring out the rules- maybe they aren't as stupidly restrictive as all that. But if he uses my el-cheapo $30 Digital Multimeter with temp probe- does that blow his budget too? What about my good $15 chemistry thermometer? What about a home PC instead of a School PC to write up his reports and generate the posters for the poster board. On No Kinko's printed them-- now his entire budget is gone. Want to Hamsters and a maze? Nope. Hamster and Costs $30. You don't have enough money for a poster board, much less materials to build a maze out of. Better capture your rodent in the wild kid (don't get rabies) and don't forget to get a receipt for it from mother nature. Otherwise how will they know you got it for "free"?
Seriously. What year do they think it is? 1975? The Budget needs to be at least $80, and probably should be closer to a $150 max. That doesn't mean anyone is obligated to spend that, but it does mean your kid can do serious project if they want to. If they wanted to do a Stirling engine, or a wimhurst generator and they wanted to build it from scratch (and yeah both would be possible to do - and I have seen stirlings made form test tubes.. that but it would require some serious machining skills) be enven then your materials costs are likely to exceed $35.