DIY Puzzle Frame
You can customize the size of the puzzle frame freely.
For example, if your puzzle is 954mm long and 349mm wide,
first adjust the size to 955mm by 350mm.
Then subtract 20mm for each corner frame piece (a total of 40mm),
which gives you 915mm by 310mm.
You can then mix and match frame pieces to fit the size you need.
For the 915mm side, you can use three 250mm pieces, one 30mm piece, one 35mm piece, and one 100mm piece, which add up to 915mm.
For the 310mm side, you can use one 250mm piece and two 30mm pieces, which together make 310mm.
You can change the combinations as you like.
Also, since each side has two edges, remember to double the quantity.