Reconfiguring these 2 Ikea Laiva bookcases resulted in a tall combo (optimal for a corner space) and a short one (good to stand on my desk).
Each pair of identical segments were combined symmetrically: lower-end to lower-end for the tall ones, and upper-end to upper-end for the short ones.
The tall combo left a huge gap in the middle, so a(t least one) shelf there was necessary…
In the vertical holes designed for the original assembly long screws I placed improvised dowels (meaning thick wooden pencils).
The shelves’ support pins are cylindrical pieces I cut from a thin & straight tree branch, then each was shaped on one end to fit in the horizontal holes around the pencil-dowels.
The shelves were cut to match the required width. (They’re not identical because those two were around, and no additional budget was approved 🙂