Hi, thank you! I'm sorry I just now saw your comment!
We used 1/8" plywood for the entire hull of the boat. Electronics were cheap-o Amazon, ebay, and Aliexpress parts. Links below are Amazon, but we found some of the same stuff much cheaper on eBay and Aliexpress, where we didn't mind waiting for long shipping times.
We're new to RC so didn't really know what we were doing. I'm sure many folks here can recommend better parts and sources, but here's what we used ->
2200kv brushless motor w/30A ESC ($13-21): https://www.amazon.com/XtremeAmazing-2200KV-Brushless-2212-6-helicopter/dp/B01M3UBGU9
SG90 Micro servo ($2/ea): https://www.amazon.com/Dorhea-Arduino-Helicopter-Airplane-Walking/dp/B07Q6JGWNV/ref=sr_1_7?dchild=1&keywords=servo&qid=1593487581&sr=8-7
Stainless propeller shaft ($12-20): https://www.amazon.com/uxcell-Propeller-Universal-L300mm-L250mm/dp/B07Q3XC3GH/ref=sr_1_11?dchild=1&keywords=rc+boat+propeller&qid=1593487695&sr=8-11
Flysky FS-i6X transmitter with receiver ($42-57): https://www.amazon.com/Flysky-FS-i6X-Transmitter-FS-iA6B-Receiver/dp/B0744DPPL8/ref=sr_1_4?crid=3HQWL6DPJ1756&dchild=1&keywords=rc+radio+transmitter+and+receiver&qid=1593487779&sprefix=rc+radio%2Caps%2C215&sr=8-4
Ovonic 3s 3000mAh lipo battery (2 for $42): https://www.amazon.com/OVONIC-Dean-Style-Connector-Airplane-Helicopter/dp/B07CVDP9DB/ref=sr_1_1?dchild=1&keywords=3s+battery+3000+ovonic&qid=1593487874&sr=8-1
(And of course we needed a good lipo battery charger.)
The cabin lights were trickier than we'd hoped. I had some 6-volt led strips laying around, but had to use a separate 9V battery to run those because the receiver only puts out about 4.4V and wouldn't turn the lights on. To get that working, we cobbled together an aux receiver switch using the circuit board from an old servo and a transistor pulled from some other old board, which allowed us to switch the lights on and off from the radio. This was pure stubbornness, though, as there are inexpensive switches that do exactly this for around $12: https://www.amazon.com/Apex-RC-Products-Electronic-Channel/dp/B07BKSGW3D/ref=sr_1_1_sspa?crid=18K21ZBV34B46&dchild=1&keywords=rc+switch+receiver+on+and+off&qid=1593488158&sprefix=rc+switch%2Caps%2C288&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzQU1BREE0TVc3VVdCJmVuY3J5cHRlZElkPUEwMDMyOTAzOUE4TEZBM1JBNlkzJmVuY3J5cHRlZEFkSWQ9QTA1NzU2MzkxRFRGTzU1V1VJRzFVJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==
Thanks again for checking it out!
-Steve