Not sure how you are making your finger joints, but they're easy and quick to make with a home-made router jig once set up. For some years now, I've house most of my homebrew projects - simple test gear, Mini-Mod 'pantry transmitter', FM'AM converter etc - in finger jointed (AKA 'comb-jointed') enclosures. Apart from being in keeping with vintage test gear and crystal sets of yesteryear, I make them from offcuts of mahogany, which don't cost me anything and can be 'made to measure'. I usually use 1/4" fingers, but they can be any size you care to make the jig for, using whatever diameter of straight-sided router bit you use.
I always cut the fingers a couple of mm longer than the need to be then when the corners have been glued up (with 'Titebond'), I clean them up on my belt sander.
I appreciate that this is a vintage radio forum - not woodworking, so I won't bang on too much about it, but have attached a pic of a test-piece not glued up or sanded, and another in two contrasting timbers to show how close-fitting the joints are with a correctly adjust jig. My jig is made from scrap, and the router cost a fiver at a car boot sale. The cheapest DIY store router is fine for this purpose.
One tip I would give, is to always place a sacrificial piece of timber behind the workpiece when cutting the slots, to avoid 'break out' as the router passes through the workpiece.
Some youtube videos of home-constructed jigs might be of interest for anyone with basic woodworking skills.
https://www.youtube.com/watch?v=BHZMdvFXMnM
https://www.youtube.com/watch?v=G01hhn-kQnc
https://www.youtube.com/watch?v=LE1Wixu7E-g
Hope that's of interest.