Pen and Paper Puzzles

Here are all of the Pen and Paper puzzle ideas I've had, including results about their viability.

Balancing Act

Each block represents a number from 1-9. No block may be resting on a smaller numbered block. Work out un-numbered blocks.

Create blocks, determine relationships and degrees of freedom, start testing numbers.

Hourglass

Flip the puzzle and allow “granules” to fall. Smallest number in the lowest row falls first and will fall to the left most space available in the top most unfilled row. Get all granules in bottom in order.

You have a grid of As, Bs, Cs, Ds. No consecutive letters may be touching. Remove all letters that infringe on this rule and then ensure that no row or column has more than one of each letter in it.

2x2 grids full of letters, take one letter from each box of four so that no letter appears twice.

A pair in each row adds to get right-hand number. Each particular pair of positions can only occur once. Can swap within rows to satisfy. Three numbers in each column which aren’t in pairs add to get bottom number.

A grid of squares that each contain 2 numbers. Choose one number in each square so that each row and column contain exactly one of each number from 1-5.

Potential for physical puzzle (but only one setup), where each square rotates to choose the digit.