There are a few different options depending on whether you want a solution to bond and seal or whether you are sealing over an existing joint.
If you want a temporary joint, you could consider 3M™ High Tack Pressure Sensitive Adhesive 3794 which is a hotmelt. If the parts are very flat, you may also get good performance from a light coating of 3M™ Super 77™ Multipurpose Spray Adhesive. The balance for a bonding adhesive is that a strong joint is often not removable. You will need to test these options in your application to verify that they have the holding strength and removability needed.
If you are sealing an existing joint, you could try a sealing tape like 3M™ Extreme Sealing Tape 4411G. For plastics like acrylic, this tape should be removable if you do not use an adhesion promoter or primer. To remove this tape, use the stretch-release method like a 3M™ Command™ Adhesive. Although we would typically consider this tape removable on these surfaces, you should test it on your materials to ensure that the level of removability meets your requirements.
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