Print upright with support enabled.
Very important: the inserts are meant for ikea skadis pegboard, not tested on different other pegboards.
13 July 2023 Update:
If you have printed the original holder, there are now two new models that uses a different set of hooks at the back so these models can be positioned to the side closely. The model offset_R is on the right of the model (look from the front) while offset_L is on the left as shown here.
The author marked this model as their own original creation.