Any circular saw will tilt the blade compared to the base so that's covered.
Box finger joints would be a reasonable connection system. You could stay quite chunky and only have 4 or 5 per corner.
Glue and screw would also work. Splined mitre joints would be a fancy but possible alternative as flipping 45° ish cut edges will give you an exact 90° joint.
Buy a cheap oil stone and some 3in1 to sharpen the chisels.
You will likely need a finer tooth circular saw blade for finish cuts.
Where are you based. Some local forumite may be willing to help with irl advice or tool loan?
Any circular saw will tilt the blade compared to the base so that's covered.
Box finger joints would be a reasonable connection system. You could stay quite chunky and only have 4 or 5 per corner.
Glue and screw would also work. Splined mitre joints would be a fancy but possible alternative as flipping 45° ish cut edges will give you an exact 90° joint.
Buy a cheap oil stone and some 3in1 to sharpen the chisels.
You will likely need a finer tooth circular saw blade for finish cuts.
Where are you based. Some local forumite may be willing to help with irl advice or tool loan?