My custom Explorer LR4 build, with the goal of keeping it as cheap as possible while still using good quality components. Used Oscar Liang's https://oscarliang.com/flywoo-explorer-lr/ tune on it and limited the motor output to 75% for 4s, as the motors I used are 3600kv. I used a stripped down Flysky FS-IA6B, with the antennas connected with a piece of heatshrink, resembling a T-antenna, and placed the receiver pcb on the top side of the back frame. Haven't had any issues with it, and still have plenty of range.

Flight time was around 15 minutes cruising with 4s 1100mah, or around 7-10 minutes when flying more aggressively, it also works well with 3s 18650 packs. Also often fly with 2s 18650s and 100% motor output and it works surpisingly well for crusing around due to the high motor kv, and doesn't feel as sluggish as the 3s/4s 18650s.

Update:
-Broke an arm due to motor desync from screwing the screws too far in, resulting in damaged windings. I designed a 3d printed replacement arm that can be found here: https://cults3d.com/en/3d-model/gadget/explorer-lr4-clone-uruav-force-lr4-178mm-front-arm-replacement-flightpro16 IMPORTANT: If using the same motors as I did, shorten the screws or use shorter screws as the supplied screws are too long if using the same frame I used with 3mm arms, otherwise these motors run very smoothly and have loads of power considering the price and the lesser known brand that they are from. I'd definetely recommend them.

-Would recommend purchasing this flight controller instead as the current one only has 2 uarts, and this one isn't that much more expensive:
https://www.aliexpress.com/item/1005006196165097.html?spm=a2g0o.detail.pcDetailTopMoreOtherSeller.10.62f1EqmFEqmFk9&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40000.327270.0&scm_id=1007.40000.327270.0&scm-url=1007.40000.327270.0&pvid=4cb56514-d8f8-4ae5-8893-fe59e81851d6&_t=gps-id:pcDetailTopMoreOtherSeller,scm-url:1007.40000.327270.0,pvid:4cb56514-d8f8-4ae5-8893-fe59e81851d6,tpp_buckets:668%232846%238116%232002&pdp_npi=4%40dis%21EUR%2126.97%2126.97%21%21%21205.27%21205.27%21%402101efd717088602131887794e7275%2112000036221503030%21rec%21AT%214190847440%21&utparam-url=scene%3ApcDetailTopMoreOtherSeller%7Cquery_from%3A