You'll probably want to determine the size of the transaction first[1]. Since there is only one output, size with respect to that is fixed, though can vary dependent on the kind of unlocking script you have. Eg. P2PKH outputs are bigger than P2WPKH output by 3 byte. The GitHub code that you should be able to find gives you the size of the various kinds of inputs (including the signature) and outputs.
-> Create the variables for the inputs and outputs to calculate the size.
Afterwhich, you can relate it to the fees that you're going to pay. The fee rates you're going to decide on will determine the kinds of outputs that you're able to use. By limiting the total fees below 1000 sat, deduce the range of acceptable transaction size based on your desired fee rates*. Next, run through the
permutations combinations of the inputs (and a fixed output), determine one that'll result in 0.03BTC as the output after deducting the estimated fees. Note that the signature size can vary slightly so I'll leave a few satoshi for the fees to compensate for the margin of error.
*Strictly speaking, due to how vague the question is, you can choose a huge range of fees (at least 1sat/vbyte) or just use whatever is left after deducting 0.03BTC to be used as the fees. Since the question doesn't state whether the transaction has to be standard, just include a range of 0-1000 sat as the fees and permutate the value of the inputs.
[1]
https://jlopp.github.io/bitcoin-transaction-size-calculator/Edited: Same mistake as above
