My family and I play a card game which can leave you with 50+ cards in your hand after picking up the discard pile. This will help the less dexterous person hold your cards.
I have personalized this one for a family member but I uploaded a basic holder that only has "card shark" on the front. The part is 50mm x 150mm x 65mm

I uploaded a new design with fewer but wider slots and left the text off labeled "barebones"